Gallery: WIRED Space Photo of the Day 2012
01The core of the Milky Way at a distance of some 26,000 light years from Earth.
Data from NASA's Great Observatories has been combined to produce this unprecedented image of the central region of the Milky Way. Near-infrared light from Hubble (yellow) outlines energetic regions where stars are being born. Infrared data from Spitzer (red) show glowing clouds of dust containing complex structures. And, X-rays from Chandra (blue and violet) reveal gas heated to millions of degrees by stellar explosion and outflows from the Galaxys supermassive black hole.
02dec-31-2012
Great Lakes of Titan -------------------- The existence of oceans or lakes of liquid methane on Saturn's moon Titan was predicted more than 20 years ago. But with a dense haze preventing a closer look it has not been possible to confirm their presence. Until the Cassini flyby of July 22, 2006, that is. Radar imaging data from the flyby, published this week in the journal Nature, provide convincing evidence for large bodies of liquid. This image, used on the journal's cover, gives a taste of what Cassini saw. Intensity in this colorized image is proportional to how much radar brightness is returned, or more specifically, the logarithm of the radar backscatter cross-section. The colors are not a representation of what the human eye would see. The lakes, darker than the surrounding terrain, are emphasized here by tinting regions of low backscatter in blue. Radar-brighter regions are shown in tan. The strip of radar imagery is foreshortened to simulate an oblique view of the highest latitude region, seen from a point to its west. This radar image was acquired by the Cassini radar instrument in synthetic aperture mode on July 22, 2006. The image is centered near 80 degrees north, 35 degrees west and is about 140 kilometers (84 miles) across. Smallest details in this image are about 500 meters (1,640 feet) across. *Image: NASA/JPL-Caltech/USGS \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA09102.jpg)\]* *Caption: [Cassini Solstice Team](http://photojournal.jpl.nasa.gov/catalog/PIA09102)*
ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit03dec-30-2012
Hidden Flames ------------- This VISTA image shows the spectacular star-forming region known as the Flame Nebula, or NGC 2024, in the constellation of Orion (the Hunter) and its surroundings. In views of this evocative object in visible light the core of the nebula is completely hidden behind obscuring dust, but in this VISTA view, taken in infrared light, the cluster of very young stars at the object’s heart is revealed. The wide-field VISTA view also includes the glow of the reflection nebula NGC 2023, just below centre, and the ghostly outline of the Horsehead Nebula (Barnard 33) towards the lower right. The bright bluish star towards the right is one of the three bright stars forming the Belt of Orion. The image was created from VISTA images taken through J, H and Ks filters in the near-infrared part of the spectrum. The image shows the full area of the VISTA field and is one degree by 1.5 degrees in extent. The total exposure time was 14 minutes. *Image: ESO/J. Emerson/VISTA. Acknowledgment: Cambridge Astronomical Survey Unit \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso0949n.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0949n/)*
04dec-29-2012
Tri-Color Sun ------------- This composite image combines EIT images from three wavelengths (171Å, 195Å and 284Å) into one that reveals solar features unique to each wavelength. Since the EIT images come to us from the spacecraft in black and white, they are color coded for easy identification. For this image, the nearly simultaneous images from May 1998 were each given a color code (red, yellow and blue) and merged into one. *Image: NASA/SOHO \[[high-resolution](http://sohowww.nascom.nasa.gov/gallery/images/large/trico1.jpg)\]* *Caption: [NASA](http://sohowww.nascom.nasa.gov/gallery/images/trico1.html)*
Chandra X-ray Observatory Center05dec-28-2012
Sparkling Galaxy Reveals Black Hole ----------------------------------- The spiral galaxy NGC 3627 is located about 30 million light years from Earth. This composite image includes X-ray data from NASA's Chandra X-ray Observatory (blue), infrared data from the Spitzer Space Telescope (red), and optical data from the Hubble Space Telescope and the Very Large Telescope (yellow). The inset shows the central region, which contains a bright X-ray source that is likely powered by material falling onto a supermassive black hole. Confirming previous Chandra results, this study finds the fraction of galaxies found to be hosting supermassive black holes is much higher than found with optical searches. This shows the ability of X-ray observations to find black holes in galaxies where relatively low-level black hole activity has either been hidden by obscuring material or washed out by the bright optical light of the galaxy. *Image: NASA/CXC/Ohio State Univ./C.Grier et al.; Optical: NASA/STScI, ESO/WFI; Infrared: NASA/JPL-Caltech \[[high-resolution](http://www.nasa.gov/images/content/716497main_chandra_sparkle_lg_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2418.html)*
06dec-27-2012
Hollows on Mercury ------------------ In the well-documented case of Eminescu's hollows, the image above provides some new insight. Though the majority of the hollows are located on and directly around the central peak, if you look closely you'll see that there are small hollows located on top of the knobby texture on the upper right side of the image. Are these hollows younger than the ones on Eminescu's central peak and floor? Are hollows currently forming in Eminescu? This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN0261771341M.map.jpg)\]* *Caption: [Mercury Messenger team](http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1045)*
07dec-26-2012
Really Hot Stars ---------------- This unique image shows AB7, one of the highest excitation nebulae in the Magellanic Clouds (MCs), two satellite galaxies of our own Milky Way. AB7 is a binary star, consisting of one WR-star — highly evolved massive star - and a mid-age massive companion of spectral type O. These exceptional stars have very strong stellar winds: they continuously eject energetic particles — like the "solar wind" from the Sun — but some 10 to 1,000 million times more intensely than our star! These powerful winds exert an enormous pressure on the surrounding interstellar material and forcefully shape those clouds into "bubbles", well visible in the photos by their blue colour. AB7 is particularly remarkable: the associated huge nebula and HeII region indicate that this star is one of the, if not the, hottest WR-star known so far, with a surface temperature in excess of 120,000 degrees ! Just outside this nebula, a small network of green filaments is visible — they are the remains of another supernova explosion. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso0310a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0310a/)*
08dec-25-2012
Merry Radio Christmas --------------------- This panorama of a section of the Milky Way in the constellations of Scutum and Aquila illustrates the dynamic interplay between the birth and death of massive stars in our Galaxy. The image is a composite of a radio image constructed from observations taken in several configurations of the Very Large Array at a wavelength of 20 cm for the MAGPIS survey with mid-infrared data taken as part of the GLIMPSE survey conducted by the Spitzer Space Telescope. The radio data are coded red, the long-wavelength infrared data (at 8 micrometers) green, and the shorter wavelength infrared data blue-white; yellow regions in the image show places where both radio and infrared emission is prominent. Normal stars are brightest at the shortest wavelengths, showing up as the myriad of blue-white points. Birthsites of the youngest massive stars show as yellow clumps -- radiation from the newborn stars heats surrounding dust producing infrared emission, while the ultraviolet light from these stars separates electrons from hydrogen atoms giving rise to radio emission. More mature stars have managed to destroy the dust nearby leaving red cores surrounded by yellow, then green, shells as the temperature drops far from the stars. The prominent red arcs mark the sites where massive stars have died in titanic explosions and blasted their gas light years into space at thousands of miles per second; their radio emission is produced as electrons, accelerated to nearly the speed of light by the outward moving blast waves, spiral in the Galactic magnetic field. The diffuse green glow reveals the tiny dust particles that suffuse interstellar space along the band of the Milky Way; dark filaments superposed on this emission show regions where the gas and dust are so thick that no light can get through -- regions in which future generations of stars will form. *Image: Image courtesy of NRAO/AUI and (Rick White, STScI) (Bob Becker, IGPP/LLNL & UC-Davis) (David Helfand, Columbia) \[[high-resolution](http://images.nrao.edu/images/birth3_death_milkyway_med.jpg)\]* *Caption: [NRAO](http://images.nrao.edu/597)*
09dec-24-2012
Colorful Large Magellanic Cloud ------------------------------- In commemoration of NASA's Hubble Space Telescope completing its 100,000th orbit in its 18th year of exploration and discovery, scientists at the Space Telescope Science Institute in Baltimore, Md., have aimed Hubble to take a snapshot of a dazzling region of celestial birth and renewal. Hubble peered into a small portion of the nebula near the star cluster NGC 2074 (upper, left). The region is a firestorm of raw stellar creation, perhaps triggered by a nearby supernova explosion. It lies about 170,000 light-years away near the Tarantula nebula, one of the most active star-forming regions in our Local Group of galaxies. The three-dimensional-looking image reveals dramatic ridges and valleys of dust, serpent-head "pillars of creation," and gaseous filaments glowing fiercely under torrential ultraviolet radiation. The region is on the edge of a dark molecular cloud that is an incubator for the birth of new stars. The high-energy radiation blazing out from clusters of hot young stars already born in NGC 2074 is sculpting the wall of the nebula by slowly eroding it away. Another young cluster may be hidden beneath a circle of brilliant blue gas at center, bottom. In this approximately 100-light-year-wide fantasy-like landscape, dark towers of dust rise above a glowing wall of gases on the surface of the molecular cloud. The seahorse-shaped pillar at lower, right is approximately 20 light-years long, roughly four times the distance between our Sun and the nearest star, Alpha Centauri. The region is in the Large Magellanic Cloud (LMC), a satellite of our Milky Way galaxy. It is a fascinating laboratory for observing star-formation regions and their evolution. Dwarf galaxies like the LMC are considered to be the primitive building blocks of larger galaxies. This representative color image was taken on August 10, 2008, with Hubble's Wide Field Planetary Camera 2. Red shows emission from sulfur atoms, green from glowing hydrogen, and blue from glowing oxygen. *Image: NASA, ESA, and M. Livio (STScI) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/2008/31/image/a/format/xlarge_web/)\]* *Caption: [Hubble Heritage site](http://hubblesite.org/newscenter/archive/releases/2008/31/image/a/)*
10dec-23-2012
Hourglass Nebula Is Watching ---------------------------- This Hubble telescope snapshot of MyCn18, a young planetary nebula, reveals that the object has an hourglass shape with an intricate pattern of "etchings" in its walls. A planetary nebula is the glowing relic of a dying, Sun-like star. The results are of great interest because they shed new light on the poorly understood ejection of stellar matter that accompanies the slow death of Sun-like stars. According to one theory on the formation of planetary nebulae, the hourglass shape is produced by the expansion of a fast stellar wind within a slowly expanding cloud, which is denser near its equator than near its poles. *Image: Raghvendra Sahai and John Trauger (JPL), the WFPC2 science team, and NASA \[[high-resolution](http://hubblesite.org/gallery/album/nebula/pr1996007b/xlarge_web/)\]* *Caption: [Hubble Heritage site](http://hubblesite.org/gallery/album/nebula/pr1996007b/)*
11dec-22-2012
Canyon Details on Mars ---------------------- Hydrae Chasma is a deep, circular depression on Mars approximately 50 kilometers across, situated between Juventae Chasma to the north and the large canyon system Valles Marineris to the south. The Chasma has steep walls flanked by numerous landslides and a massive scarp along its southern boundary where the surface has collapsed into this depression. This closeup is of an isolated flat-topped mountain (known as a mesa) rising out of a sea of dunes located in the center of Hydrae Chasma. Darker-toned dunes, likely composed of basaltic sands, form an apron along the base of the mesa's northern margin. The western side of the mesa is gently sloping and is composed of a highly fractured light-toned rubbly base. It is overlaid by alternating light and dark layered cliff-forming units and is covered by a sediment cap containing still more dunes. The layered sequences are present only in the interior deposits and not in the walls of the Chasma. Similar deposits are located on the floors of Valles Marineris and other chasmata and may be the sediment remnants of ancient lakes formed within these canyon systems. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2880/ESP_029516_1730.jpg)\]* *Caption: [Ginny Gulick](http://hirise.lpl.arizona.edu/ESP_029516_1730)*
12dec-21-2012
Star Making Waves ----------------- The giant star Zeta Ophiuchi is having a "shocking" effect on the surrounding dust clouds in this infrared image from NASA's Spitzer Space Telescope. Stellar winds flowing out from this fast-moving star are making ripples in the dust as it approaches, creating a bow shock seen as glowing gossamer threads, which, for this star, are only seen in infrared light. Zeta Ophiuchi is a young, large and hot star located around 370 light-years away. It dwarfs our own sun in many ways -- it is about six times hotter, eight times wider, 20 times more massive, and about 80,000 times as bright. Even at its great distance, it would be one of the brightest stars in the sky were it not largely obscured by foreground dust clouds. This massive star is travelling at a snappy pace of about 54,000 mph (24 kilometers per second), fast enough to break the sound barrier in the surrounding interstellar material. Because of this motion, it creates a spectacular bow shock ahead of its direction of travel (to the left). The structure is analogous to the ripples that precede the bow of a ship as it moves through the water, or the sonic boom of an airplane hitting supersonic speeds. The fine filaments of dust surrounding the star glow primarily at shorter infrared wavelengths, rendered here in green. The area of the shock pops out dramatically at longer infrared wavelengths, creating the red highlights. A bright bow shock like this would normally be seen in visible light as well, but because it is hidden behind a curtain of dust, only the longer infrared wavelengths of light seen by Spitzer can reach us. Bow shocks are commonly seen when two different regions of gas and dust slam into one another. Zeta Ophiuchi, like other massive stars, generates a strong wind of hot gas particles flowing out from its surface. This expanding wind collides with the tenuous clouds of interstellar gas and dust about half a light-year away from the star, which is almost 800 times the distance from the sun to Pluto. The speed of the winds added to the star's supersonic motion result in the spectacular collision seen here. Our own sun has significantly weaker solar winds and is passing much more slowly through our galactic neighborhood so it may not have a bow shock at all. NASA's twin Voyager spacecraft are headed away from the solar system and are currently about three times farther out than Pluto. They will likely pass beyond the influence of the sun into interstellar space in the next few years, though this is a much gentler transition than that seen around Zeta Ophiuchi. For this Spitzer image, infrared light at wavelengths of 3.6 and 4.5 microns is rendered in blue, 8.0 microns in green, and 24 microns in red. *Image: NASA/JPL-Caltech \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA16604.jpg)\]* *Caption: [NASA/JPL](http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA16604)*
13dec-20-2012
Cygnus Loop Filaments --------------------- As an end of the year finale, the National Optical Astronomy Observatory (NOAO) and WIYN partners offer this new wide-field image of the Cygnus loop. Three degrees on a side, this image covers an area of the sky about 45 times that of the full moon. But it does so without sacrificing high resolution. The image is over 600 million pixels in size, making it one of the largest astronomical images ever made. The Cygnus Loop is a large supernova remnant: the gaseous remains of a massive star that exploded long ago. It is located about 1,500 light-years from Earth in the direction of the constellation Cygnus, the Swan. Astronomers estimate the supernova explosion that produced the nebula occurred between 5,000 to 10,000 years ago. First noted in 1784 by William Herschel, it is so large that its many parts have been catalogued as separate objects, including NGC 6992, NGC 6995 and IC 1340 along the eastern (left) side of the image, NGC 6974 and NGC 6979 near the top-center, and the Veil Nebula (NGC 6960) and Pickering’s Triangle along the western (right) edge. The bright star near the western edge of the image, known as 52 Cygnus, is not associated with the supernova. The data were obtained with the NOAO Mosaic 1 camera, with observations in the Oxygen \[OIII\] (blue), Sulphur \[S II\] (green) and Hydrogen-Alpha (red) filters. When mounted on the WIYN 0.9 meter telescope the Mosaic camera has a one square degree field of view. The Cygnus Loop was observed with nine separate telescope pointings in a 3x3 grid pattern. The observations were originally obtained in 2003 by Richard Cool, while he was a graduate student at the University of Arizona, as part of a project to precisely measure the distance to the Cygnus Loop. Dr. Cool, now at the MMT Observatory in Arizona, said, “Often, astronomical research reduces images to dry tables of numerical information that we analyze in order to more deeply understand our universe. Images like this are amazing because they can remind you of the big picture and beauty that surrounds us”. In 2003 the computing power available was insufficient to process the data into a single, full-resolution color image. Nine years later, the data were re-reduced and processed by Travis Rector to create the image presented here. Dr. Rector has produced a remarkable series of color images from NOAO telescopes. They can be found at his website and on a dedicated NOAO image gallery page. Images like this demonstrate that even relatively small telescopes when equipped with modern cameras are capable of producing cutting-edge research. The 0.9 meter telescope at Kitt Peak is operated by the WIYN Consortium. It has been in operation since 1960, when the original telescope was first installed at the site now occupied by the WIYN 3.5 meter telescope. Today, the 0.9 meter is regularly used by graduate students and faculty for a variety of research projects. The WIYN 0.9 meter Observatory is a partnership including Austin Peay State University, Haverford College, Indiana University, Rochester Institute of Technology, San Francisco State University, University of Wisconsin-Madison, University of Wisconsin- Stevens Point, University of Wisconsin-Whitewater, and Wisconsin Space Grant consortium. NOAO is operated by Association of Universities for Research in Astronomy Inc. (AURA) under a cooperative agreement with the National Science Foundation. *Image: T.A. Rector (University of Alaska Anchorage), Richard Cool (University of Arizona) and WIYN/NOAO/AURA/NSF \[[high-resolution](http://www.noao.edu/image_gallery/images/d7/cygloop-2000.jpg)\]* *Caption: [NOAO](http://www.noao.edu/news/2012/pr1209.php)*
14dec-19-2012
Back-Lit Saturn --------------- NASA's Cassini spacecraft has delivered a glorious view of Saturn, taken while the spacecraft was in Saturn's shadow. The cameras were turned toward Saturn and the sun so that the planet and rings are backlit. (The sun is behind the planet, which is shielding the cameras from direct sunlight.) In addition to the visual splendor, this special, very-high-phase viewing geometry lets scientists study ring and atmosphere phenomena not easily seen at a lower phase. Since images like this can only be taken while the sun is behind the planet, this beautiful view is all the more precious for its rarity. The last time Cassini captured a view like this was in Sept. 2006, when it captured a mosaic processed to look like natural color, entitled "In Saturn's Shadow". In that mosaic, planet Earth put in a special appearance, making "In Saturn's Shadow" one of the most popular Cassini images to date. Earth does not appear in this mosaic as it is hidden behind the planet. Also captured in this image are two of Saturn's moons: Enceladus and Tethys. Both appear on the left side of the planet, below the rings. Enceladus is closer to the rings; Tethys is below and to the left. This view looks toward the non-illuminated side of the rings from about 19 degrees below the ring plane. Images taken using infrared, red and violet spectral filters were combined to create this enhanced-color view. The images were obtained with the Cassini spacecraft wide-angle camera on Oct. 17, 2012 at a distance of approximately 500,000 miles (800,000 kilometers) from Saturn. Image scale at Saturn is about 30 miles per pixel (50 kilometers per pixel). *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA14934.jpg)\]* *Caption: [Cassini Solstice team](http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA14934)*
NASA, ESA and the Hubble Heritage Team (STScI/AURA)15dec-18-2012
Planetary Nebula Ornament ------------------------- The NASA/ESA Hubble Space Telescope celebrates the holiday season with a striking image of the planetary nebula NGC 5189. The intricate structure of the stellar eruption looks like a giant and brightly coloured ribbon in space. *Image: NASA, ESA and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/heic1220a.jpg)\]* *Caption: [Hubble Heritage team](http://www.spacetelescope.org/images/heic1220a/)*
16dec-17-2012
Tectonics on Enceladus ---------------------- On Oct. 5, 2008, just after coming within 25 kilometers (15.6 miles) of the surface of Enceladus, NASA's Cassini captured this stunning mosaic as the spacecraft sped away from this geologically active moon of Saturn. Craters and cratered terrains are rare in this view of the southern region of the moon's Saturn-facing hemisphere. Instead, the surface is replete with fractures, folds, and ridges—all hallmarks of remarkable tectonic activity for a relatively small world. In this enhanced-color view, regions that appear blue-green are thought to be coated with larger grains than those that appear white or gray. Portions of the tiger stripe fractures, or sulci, are visible along the terminator at lower right, surrounded by a circumpolar belt of mountains. The icy moon's famed jets emanate from at least eight distinct source regions, which lie on or near the tiger stripes. However, in this view, the most prominent feature is Labtayt Sulci, the approximately one-kilometer (0.6 miles) deep northward-trending chasm located just above the center of the mosaic. Near the top, the conspicuous ridges are Ebony and Cufa Dorsae. This false-color mosaic was created from 28 images obtained at seven footprints, or pointing positions, by Cassini's narrow-angle camera. At each footprint, four images using filters sensitive to ultraviolet, visible and infrared light (spanning wavelengths from 338 to 930 nanometers) were combined to create the individual frames. The mosaic is an orthographic projection centered at 64.49 degrees south latitude, 283.87 west longitude, and it has an image scale of 196 kilometers (122.5 miles) per pixel. The original images ranged in resolution from 180 meters (594 feet) to 288 meters (950 feet) per pixel and were acquired at distances ranging from 30,000 to 48,000 kilometers (18,750 to 30,000 miles) as the spacecraft receded from Enceladus. The view was acquired at a Sun-Enceladus-spacecraft, or phase, angle of 73 degrees. *Image: NASA/JPL/Space Science Institute \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA11133.jpg)\]* *Caption: [NASA](http://photojournal.jpl.nasa.gov/catalog/PIA11133)*
ESO/R. Chini17dec-16-2012
Painted Swan Nebula ------------------- Astronomers using data from ESO's Very Large Telescope (VLT), at the Paranal Observatory in Chile, have made an impressive composite of the nebula Messier 17, also known as the Omega Nebula or the Swan Nebula. The painting-like image shows vast clouds of gas and dust illuminated by the intense radiation from young stars. The image shows a central region about 15 light-years across, although the entire nebula is even larger, about 40 light-years in total. Messier 17 is in the constellation of Sagittarius (the Archer), about 6000 light-years from Earth. It is a popular target for amateur astronomers, who can obtain good quality images using small telescopes. These deep VLT observations were made at near-infrared wavelengths with the ISAAC instrument. The filters used were J (1.25 µm, shown in blue), H (1.6 µm, shown in green), and K (2.2 µm, shown in red). In the centre of the image is a cluster of massive young stars whose intense radiation makes the surrounding hydrogen gas glow. To the lower right of the cluster is a huge cloud of molecular gas. At visible wavelengths, dust grains in the cloud obscure our view, but by observing in infrared light, the glow of the hydrogen gas behind the cloud can be seen shining faintly through. Hidden in this region, which has a dark reddish appearance, the astronomers found the opaque silhouette of a disc of gas and dust. Although it is small in this image, the disc has a diameter of about 20 000 AU, dwarfing our Solar System (1 AU is the distance between the Earth and the Sun). It is thought that this disc is rotating and feeding material onto a central protostar — an early stage in the formation of a new star. *Image: ESO/R. Chini \[[high-resolution](http://www.eso.org/public/archives/images/screen/potw1044a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/potw1044a/)*
18dec-15-2012
Galactic Pinwheel ----------------- A nearly perfect ring of hot, blue stars pinwheels about the yellow nucleus of an unusual galaxy known as Hoag's Object. This image from NASA's Hubble Space Telescope captures a face-on view of the galaxy's ring of stars, revealing more detail than any existing photo of this object. The image may help astronomers unravel clues on how such strange objects form. The entire galaxy is about 120,000 light-years wide, which is slightly larger than our Milky Way Galaxy. The blue ring, which is dominated by clusters of young, massive stars, contrasts sharply with the yellow nucleus of mostly older stars. What appears to be a "gap" separating the two stellar populations may actually contain some star clusters that are almost too faint to see. Curiously, an object that bears an uncanny resemblance to Hoag's Object can be seen in the gap at the one o'clock position. The object is probably a background ring galaxy. Ring-shaped galaxies can form in several different ways. One possible scenario is through a collision with another galaxy. Sometimes the second galaxy speeds through the first, leaving a "splash" of star formation. But in Hoag's Object there is no sign of the second galaxy, which leads to the suspicion that the blue ring of stars may be the shredded remains of a galaxy that passed nearby. Some astronomers estimate that the encounter occurred about 2 to 3 billion years ago. This unusual galaxy was discovered in 1950 by astronomer Art Hoag. Hoag thought the smoke-ring-like object resembled a planetary nebula, the glowing remains of a Sun-like star. But he quickly discounted that possibility, suggesting that the mysterious object was most likely a galaxy. Observations in the 1970s confirmed this prediction, though many of the details of Hoag's galaxy remain a mystery. The galaxy is 600 million light-years away in the constellation Serpens. The Wide Field and Planetary Camera 2 took this image on July 9, 2001. *Image: NASA and The Hubble Heritage Team (STScI/AURA) Acknowledgment: Ray A. Lucas (STScI/AURA) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2002-21-a-full_jpg.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2002/21/image/a/)*
19dec-14-2012
Shooting Star From Space ------------------------ This astronaut photograph, taken from the International Space Station while over China (approximately 400 kilometers to the northwest of Beijing), provides the unusual perspective of looking down on a meteor as it passes through the atmosphere. The image was taken on August 13, 2011, during the Perseid Meteor Shower that occurs every August. *Image: NASA \[[high-resolution](http://solarsystem.nasa.gov/multimedia/gallery/ISS028-E-024847_lrg.jpg)\]* *Caption: [NASA](http://solarsystem.nasa.gov/multimedia/display.cfm?Category=GreatShots&IM_ID=15363)*
20dec-13-2012
Giant Star Factory ------------------ Stars are sometimes born in the midst of chaos. About 3 million years ago in the nearby galaxy M33, a large cloud of gas spawned dense internal knots which gravitationally collapsed to form stars. NGC 604 was so large, however, it could form enough stars to make a globular cluster. Many young stars from this cloud are visible in this image from the Hubble Space Telescope, along with what is left of the initial gas cloud. Some stars were so massive they have already evolved and exploded in a supernova. The brightest stars that are left emit light so energetic that they create one of the largest clouds of ionized hydrogen gas known, comparable to the Tarantula Nebula in our Milky Way's close neighbor, the Large Magellanic Cloud. *Image: NASA \[[high-resolution](http://www.nasa.gov/images/content/713687main_apod_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2409.html)*
21dec-12-2012
5 Galaxy Pile-Up ---------------- A clash among members of a famous galaxy quintet reveals an assortment of stars across a wide colour range, from young, blue stars to aging, red stars. This portrait of Stephan's Quintet, also known as the Hickson Compact Group 92, was taken by the new Wide Field Camera 3 (WFC3) aboard the NASA/ESA Hubble Space Telescope. Stephan's Quintet, as the name implies, is a group of five galaxies. The name, however, is a bit of a misnomer. Studies have shown that group member NGC 7320, at upper left, is actually a foreground galaxy that is about seven times closer to Earth than the rest of the group. Three of the galaxies have distorted shapes, elongated spiral arms, and long, gaseous tidal tails containing myriad star clusters, proof of their close encounters. These interactions have sparked a frenzy of star birth in the central pair of galaxies. This drama is being played out against a rich backdrop of faraway galaxies. The image, taken in visible and near-infrared light, showcases WFC3's broad wavelength range. The colours trace the ages of the stellar populations, showing that star birth occurred at different epochs, stretching over hundreds of millions of years. The camera's infrared vision also peers through curtains of dust to see groupings of stars that cannot be seen in visible light. NGC 7319, at top right, is a barred spiral with distinct spiral arms that follow nearly 180 degrees back to the bar. The blue specks in the spiral arm at the top of NGC 7319 and the red dots just above and to the right of the core are clusters of many thousands of stars. Most of the Quintet is too far away even for Hubble to resolve individual stars. Continuing clockwise, the next galaxy appears to have two cores, but it is actually two galaxies, NGC 7318A and NGC 7318B. Encircling the galaxies are young, bright blue star clusters and pinkish clouds of glowing hydrogen where infant stars are being born. These stars are less than 10 million years old and have not yet blown away their natal cloud. Far away from the galaxies, at right, is a patch of intergalactic space where many star clusters are forming. NGC 7317, at bottom left, is a normal-looking elliptical galaxy that is less affected by the interactions. Sharply contrasting with these galaxies is the dwarf galaxy NGC 7320 at upper left. Bursts of star formation are occurring in the galaxy's disc, as seen by the blue and pink dots. In this galaxy, Hubble can resolve individual stars, evidence that NGC 7320 is closer to Earth. NGC 7320 is 40 million light-years from Earth. The other members of the Quintet reside about 300 million light-years away in the constellation Pegasus. These more distant members are markedly redder than the foreground galaxy, suggesting that older stars reside in their cores. The stars' light also may be further reddened by dust stirred up in the encounters. Spied by Edouard M. Stephan in 1877, Stephan's Quintet is the first compact group ever discovered. WFC3 observed the Quintet in July and August 2009. The composite image was made by using filters that isolate light from the blue, green and infrared portions of the spectrum, as well as emission from ionised hydrogen. These Hubble observations are part of the Hubble Servicing Mission 4 Early Release Observations. NASA astronauts installed the WFC3 camera during a servicing mission in May to upgrade and repair the 19-year-old Hubble telescope. *Image: NASA, ESA and the Hubble SM4 ERO Team \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/heic0910i.jpg)\]* *Caption: [Hubble Heritage Team](http://www.spacetelescope.org/images/heic0910i/)*
22dec-11-2012
Evaporating Rocks on Mercury ---------------------------- The bright material on the floor of Kertész crater is not the water ice recently confirmed to be in craters near Mercury's poles, but it might well be behaving as ice would on another planet. Mercury's daytime temperatures are so hot at most latitudes that rocks that would be stable at other places in the Solar System may essentially evaporate on Mercury. That is one theory for the formation of these bright, irregular features known as hollows seen here and in many other craters on Mercury. This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN0261598284M.nomap.jpg)\]* *Caption: [Mercury MESSENGER Team](http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=1036)*
ESA/Hubble & NASA23dec-10-2012
Lonely Planetary Nebula ----------------------- Located in a relatively vacant region of space about 4200 light-years away and difficult to see using an amateur telescope, the lonesome planetary nebula NGC 7354 is often overlooked. However, thanks to this image captured by the NASA/ESA Hubble Space Telescope we are able to see this brilliant ball of smoky light in spectacular detail. Just as shooting stars are not actually stars and lava lamps do not actually contain lava, planetary nebulae have nothing to do with planets. The name was coined by Sir William Herschel because when he first viewed a planetary nebula through a telescope, he could only identify a hazy smoky sphere, similar to gaseous planets such as Uranus. The name has stuck even though modern telescopes make it obvious that these objects are not planets at all, but the glowing gassy outer layers thrown off by a hot dying star. It is believed that winds from the central star play an important role in determining the shape and morphology of planetary nebulae. The structure of NGC 7354 is relatively easy to distinguish. It consists of a circular outer shell, an elliptical inner shell, a collection of bright knots roughly concentrated in the middle and two symmetrical jets shooting out from either side. Research suggests that these features could be due to a companion central star, however the presence of a second star in NGC 7354 is yet to be confirmed. NGC 7354 resides in Cepheus, a constellation named after the mythical King Cepheus of Aethiopia and is about half a light-year in diameter. A version of this image was entered into the Hubble’s Hidden Treasures image processing competition by contestant Bruno Conti. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1250a.jpg)\]* *Caption: [Hubble Heritage site](http://www.spacetelescope.org/images/potw1250a/)*
24dec-9-2012
Star Formation in Carina ------------------------ The spectacular star-forming Carina Nebula has been captured in great detail by the VLT Survey Telescope at ESO’s Paranal Observatory. This picture was taken with the help of Sebastián Piñera, President of Chile, during his visit to the observatory on 5 June 2012 and released on the occasion of the new telescope’s inauguration in Naples on 6 December 2012. *Image: ESO. Acknowledgement: VPHAS+ Consortium/Cambridge Astronomical Survey Unit \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1250a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso1250a/)*
25dec-8-2012
Winter Mars Craters ------------------- The high-resolution stereo camera on ESA’s Mars Express imaged the Charitum Montes region of the Red Planet on 18 June, near to Gale crater and the Argyre basin featured in our October and November image releases. The brighter features, giving the image an ethereal winter-like feel in the colour images, are surfaces covered with seasonal carbon dioxide frost. Charitum Montes are a large group of rugged mountains extending over almost 1000 km and bounding the southernmost rim of the Argyre impact basin. They can be seen from Earth through larger telescope and were named by Eugène Michel Antoniadi (1870–1944) in his 1929 work La Planète Mars. The images in this release all show the region’s old and highly-sculpted terrain, pockmarked with many large craters, all of which have been substantially filled in. The whole region is dusted with brighter carbon dioxide frost. *Image: ESA/DLR/FU Berlin (G. Neukum) \[[high-resolution](http://esamultimedia.esa.int/images/Science/579-20121120-10778-co-CharitumMontes_H1.jpg)\]* *Caption: [ESA](http://www.esa.int/SPECIALS/Mars_Express/SEMH7W2ABAH_0.html#subhead1)*
26dec-7-2012
Infrared Orion -------------- Looking like a pair of eyeglasses only a rock star would wear, this nebula brings into focus a murky region of star formation. NASA's Spitzer Space Telescope exposes the depths of this dusty nebula with its infrared vision, showing stellar infants that are lost behind dark clouds when viewed in visible light. Best known as Messier 78, the two round greenish nebulae are actually cavities carved out of the surrounding dark dust clouds. The extended dust is mostly dark, even to Spitzer's view, but the edges show up in mid-wavelength infrared light as glowing, red frames surrounding the bright interiors. Messier 78 is easily seen in small telescopes in the constellation of Orion, just to the northeast of Orion's belt, but looks strikingly different, with dominant, dark swaths of dust. Spitzer's infrared eyes penetrate this dust, revealing the glowing interior of the nebulae. The light from young, newborn stars are starting to carve out cavities within the dust, and eventually, this will become a larger nebula like the "green ring" imaged by Spitzer. A string of baby stars that have yet to burn their way through their natal shells can be seen as red pinpoints on the outside of the nebula. Eventually these will blossom into their own glowing balls, turning this two-eyed eyeglass into a many-eyed monster of a nebula. This is a three-color composite that shows infrared observations from two Spitzer instruments. Blue represents 3.6- and 4.5-micron light, and green shows light of 5.8 and 8 microns, both captured by Spitzer's infrared array camera. Red is 24-micron light detected by Spitzer's multiband imaging photometer. *Image: NASA/JPL-Caltech \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA14106.jpg)\]* *Caption: [NASA](http://photojournal.jpl.nasa.gov/catalog/PIA14106)*
27dec-6-2012
Galactic Bullseye ----------------- Bright pink nebulae almost completely encircle a spiral galaxy in this NASA/ESA Hubble Space Telescope image of NGC 922. The ring structure and the galaxy’s distorted spiral shape result from a smaller galaxy scoring a cosmic bullseye, hitting the centre of NGC 922 some 330 million years ago. In Hubble’s image, NGC 922 clearly reveals itself not to be a normal spiral galaxy. The spiral arms are disrupted, a stream of stars extends out towards the top of the image, and a bright ring of nebulae encircles the core. Observing with NASA’s Chandra X-ray Observatory reveals more chaos in the form of ultraluminous X-ray sources dotted around the galaxy. NGC 922’s current unusual form is a result of a cosmic bullseye millions of years ago. A smaller galaxy, catalogued as 2MASXI J0224301-244443, plunged right through the heart of NGC 922 and shot out the other side. In wide-field views of the NGC 922, the small interloper can be still be seen shooting away from the scene of the crash. As the small galaxy passed through the middle of NGC 922, it set up ripples that disrupted the clouds of gas, and triggered the formation of new stars whose radiation then lit up the remaining gas. The bright pink colour of the resulting nebulae is a characteristic sign of this process, and it is caused by excited hydrogen gas (the dominant element in interstellar gas clouds). This process of excitation and emission of light by gases is similar to that in neon signs. In theory, if two galaxies are aligned just right, with the small one passing through the centre of the larger one, the ring of nebulae should form a perfect circle, but more often the two galaxies are slightly off kilter, leading to a circle that, like this one, is noticeably brighter on one side than the other. These objects, called collisional ring galaxies, are relatively rare in our cosmic neighbourhood. Although galaxy collisions and mergers are commonplace, the precise alignment and ratio of sizes necessary to form a ring like this is not, and the ring-like phenomenon is also thought to be relatively short-lived. The chances of seeing one of these galaxies nearby is therefore quite low. Despite the immense number of galaxies in the Universe, this is one of only a handful known in our cosmic neighbourhood (the Cartwheel Galaxy, see potw1036a, being the most famous example). Observations of the more distant Universe (where we see further into the past) show that these rings were more common in the past, however. Hubble’s image of NGC 922 consists of a series of exposures taken in visible light with Hubble’s Wide Field Camera 3, and in visible and near-infrared light with the Wide Field and Planetary Camera 2. *Image: NASA, ESA. Acknowledgement: Nick Rose \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/heic1218a.jpg)\]* *Caption: [Hubble Heritage team](http://www.spacetelescope.org/news/heic1218/)*
28dec-5-2012
The Sun's Inner Atmosphere -------------------------- This combined image from Nov. 8-9, 2012, shows the sun's innermost atmosphere as seen by the Solar Dynamics Observatory (SDO) inside a larger image provided by the Solar and Heliospheric Observatory (SOHO). A coronal mass ejection can be seen traveling away from the sun in the upper right corner. Scientists can compare the images to correlate what's happening close to the sun with what happens further away. *Image: ESA/NASA \[[high-resolution](http://www.nasa.gov/images/content/711481main_709680main_HaloCMEcombo-orig_full_full.jpeg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2404.html)*
29dec-4-2012
Glittery Galaxy --------------- The brilliant cascade of stars through the middle of this image is the galaxy ESO 318-13 as seen by the NASA/ESA Hubble Space Telescope. Despite being located millions of light-years from Earth, the stars captured in this image are so bright and clear you could almost attempt to count them. Although ESO 318-13 is the main event in this image, it is sandwiched between a vast collection of bright celestial objects. Several stars near and far dazzle in comparison to the neat dusting contained within the galaxy. One that particularly stands out is located near the centre of the image, and looks like an extremely bright star located within the galaxy. This is, however, a trick of perspective. The star is located in the Milky Way, our own galaxy, and it shines so brightly because it is so much closer to us than ESO 318-13. There are also a number of tiny glowing discs scattered throughout the frame that are more distant galaxies. In the top right corner, an elliptical galaxy can be clearly seen, a galaxy which is much larger but more distant than ESO 318-13. More interestingly, peeking through the ESO 318-13, near the right-hand edge of the image, is a distant spiral galaxy. Galaxies are largely made up of empty space; the stars within them only take up a small volume, and providing a galaxy is not too dusty, it can be largely transparent to light coming from the background. This makes overlapping galaxies like these quite common. One particularly dramatic example of this phenomenon is the galaxy pair NGC 3314 (heic1208). *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1249a.jpg)\]* *Caption: [Hubble Heritage team](http://www.spacetelescope.org/images/potw1249a/)*
30dec-3-2012
Saturn and Tiny Tethys ---------------------- Tethys may not be tiny by normal standards, but when it is captured alongside Saturn, it can't help but seem pretty small. Even Saturn's rings appear to dwarf Tethys (660 miles, or 1,062 kilometers across), which is in the upper left of the image, although scientists believe the moon to be many times more massive than the entire ring system combined. This view looks toward the unilluminated side of the rings from about 18 degrees below the ringplane. The image was taken in green light with the Cassini spacecraft wide-angle camera on Aug. 19, 2012. The view was acquired at a distance of approximately 1.5 million miles (2.4 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 63 degrees. Image scale is 86 miles (138 kilometers) per pixel. *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://www.nasa.gov/images/content/708939main_PIA14636_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/cassini/multimedia/pia14636.html)*
31dec-2-2012
Sinuous Filament of Cosmic Dust ------------------------------- This image from the APEX telescope, of part of the Taurus Molecular Cloud, shows a sinuous filament of cosmic dust more than ten light-years long. In it, newborn stars are hidden, and dense clouds of gas are on the verge of collapsing to form yet more stars. The cosmic dust grains are so cold that observations at submillimetre wavelengths, such as these made by the LABOCA camera on APEX, are needed to detect their faint glow. This image shows two regions in the cloud: the upper-right part of the filament shown here is Barnard 211, while the lower-left part is Barnard 213. The submillimetre-wavelength observations from the LABOCA camera on APEX, which reveal the heat glow of the cosmic dust grains, are shown here in orange tones. They are superimposed on a visible-light image of the region, which shows the rich background of stars. The bright star above the filament is φ Tauri. *Image: ESO/APEX (MPIfR/ESO/OSO)/A. Hacar et al./Digitized Sky Survey 2. Acknowledgment: Davide De Martin \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1209a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso1209a/)*
32dec-1-2012
Eskimo Nebula ------------- In its first glimpse of the heavens following the successful December 1999 servicing mission, NASA's Hubble Space Telescope has captured a majestic view of a planetary nebula, the glowing remains of a dying, Sun-like star. This stellar relic, first spied by William Herschel in 1787, is nicknamed the "Eskimo" Nebula (NGC 2392) because, when viewed through ground-based telescopes, it resembles a face surrounded by a fur parka. In this Hubble telescope image, the "parka" is really a disk of material embellished with a ring of comet-shaped objects, with their tails streaming away from the central, dying star. The Eskimo's "face" also contains some fascinating details. Although this bright central region resembles a ball of twine, it is, in reality, a bubble of material being blown into space by the central star's intense "wind" of high-speed material. The planetary nebula began forming about 10,000 years ago, when the dying star began flinging material into space. The nebula is composed of two elliptically shaped lobes of matter streaming above and below the dying star. In this photo, one bubble lies in front of the other, obscuring part of the second lobe. Scientists believe that a ring of dense material around the star's equator, ejected during its red giant phase, created the nebula's shape. This dense waist of material is plodding along at 72,000 miles per hour (115,000 kilometers per hour), preventing high-velocity stellar winds from pushing matter along the equator. Instead, the 900,000-mile-per-hour (1.5-million-kilometer-per-hour) winds are sweeping the material above and below the star, creating the elongated bubbles. The bubbles are not smooth like balloons but have filaments of denser matter. Each bubble is about 1 light-year long and about half a light-year wide. Scientists are still puzzled about the origin of the comet-shaped features in the "parka." One possible explanation is that these objects formed from a collision of slow- and fast-moving gases. The Eskimo Nebula is about 5,000 light-years from Earth in the constellation Gemini. The picture was taken Jan. 10 and 11, 2000, with the Wide Field and Planetary Camera 2. The nebula's glowing gases produce the colors in this image: nitrogen (red), hydrogen (green), oxygen (blue), and helium (violet). *Image: NASA, Andrew Fruchter and the ERO Team \[Sylvia Baggett (STScI), Richard Hook (ST-ECF), Zoltan Levay (STScI)\] \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2000-07-a-full_jpg.jpg)\]* *Caption: [Hubble Heritage site](http://hubblesite.org/newscenter/archive/releases/2000/07/image/a/)*
33nov-30-2012
Height on the Moon ------------------ This new topographic map, from Arizona State University in Tempe, shows the surface shape and features over nearly the entire Moon with a pixel scale close to 100 m (328 feet). A single measure of elevation (one pixel) is about the size of two football fields placed side-by-side. This map was created based on data acquired by NASA's Lunar Reconnaissance Orbiter's (LRO) WAC, which is part of the LROC imaging system. The LROC imaging system consists of two Narrow Angle Cameras (NACs) to provide high-resolution images, and the WAC to provide 100-m resolution images in seven color bands over a 57-km (35-mile) swath. *Image: GSFC/DLR/ASU \[[high-resolution](http://solarsystem.nasa.gov/multimedia/gallery/604359main_WAC_CSHADE_O000N1800_1000.jpg)\]* *Caption: [NASA](http://solarsystem.nasa.gov/multimedia/display.cfm?Category=Planets&IM_ID=12803)*
34nov-29-2012
Jets of Hercules ---------------- Spectacular jets powered by the gravitational energy of a supermassive black hole in the core of the elliptical galaxy Hercules A illustrate the combined imaging power of two of astronomy's cutting-edge tools, the Hubble Space Telescope's Wide Field Camera 3, and the recently upgraded Karl G. Jansky Very Large Array (VLA) radio telescope in New Mexico. Some two billion light-years away, the yellowish elliptical galaxy in the center of the image appears quite ordinary as seen by Hubble in visible wavelengths of light. The galaxy is roughly 1,000 times more massive than the Milky Way and harbors a 2.5-billion-solar-mass central black hole that is 1,000 times more massive than the black hole in the Milky Way. But the innocuous-looking galaxy, also known as 3C 348, has long been known as the brightest radio-emitting object in the constellation Hercules. Emitting nearly a billion times more power in radio wavelengths than our Sun, the galaxy is one of the brightest extragalactic radio sources in the entire sky. The VLA radio data reveal enormous, optically invisible jets that, at one-and-a-half million light-years wide, dwarf the visible galaxy from which they emerge. The jets are very-high-energy plasma beams, subatomic particles and magnetic fields shot at nearly the speed of light from the vicinity of the black hole. The outer portions of both jets show unusual ring-like structures suggesting a history of multiple outbursts from the supermassive black hole at the center of the galaxy. The innermost parts of the jets are not visible because of the extreme velocity of the material, which causes relativistic effects that beam the light away from us. Far from the galaxy, the jets become unstable and break up into the rings and wisps. The entire radio source is surrounded by a very hot, X-ray-emitting cloud of gas, not seen in this optical-radio composite. Hubble's view of the field also shows a companion elliptical galaxy very close to the center of the optical-radio source, which may be merging with the central galaxy. Several other elliptical and spiral galaxies that are visible in the Hubble data may be members of a cluster of galaxies. Hercules A is by far the brightest and most massive galaxy in the cluster. *Image: NASA, ESA, S. Baum and C. O'Dea (RIT), R. Perley and W. Cotton (NRAO/AUI/NSF), and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2012-47-a-print.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2012/47/image/a/)*
35nov-28-2012
The Great Attractor ------------------- This image shows the central region of the Great Attractor at the original resolution of the WFI. Note the strong warping of the galaxy to the left of the center, which may be caused by gravitational interaction with one or both of the bright galaxies that are seen above and below it. The field shown measures about 12 x 12 arcmin 2. Five exposures each were made in blue (B-band filter; 5 x 300 sec), red (R-band filter; 5 x 180 sec) and near-infrared (narrow-band filter centered at 816 nm; 5 x 240 sec) light and combined into a false-colour composite by using blue, green, and red colour for the three images, respectively. A logarithmic intensity scale is used to better show the inner as well as the outer regions of the galaxies in this field. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso9954d.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso9954d/)*
36nov-27-2012
Galaxy Rose ----------- In celebration of the 21st anniversary of the Hubble Space Telescope's deployment into space, astronomers at the Space Telescope Science Institute in Baltimore, Md., pointed Hubble's eye to an especially photogenic group of interacting galaxies called Arp 273. The larger of the spiral galaxies, known as UGC 1810, has a disk that is tidally distorted into a rose-like shape by the gravitational tidal pull of the companion galaxy below it, known as UGC 1813. A swath of blue jewels across the top is the combined light from clusters of intensely bright and hot young blue stars. These massive stars glow fiercely in ultraviolet light. The smaller, nearly edge-on companion shows distinct signs of intense star formation at its nucleus, perhaps triggered by the encounter with the companion galaxy. A series of uncommon spiral patterns in the large galaxy is a tell-tale sign of interaction. The large, outer arm appears partially as a ring, a feature seen when interacting galaxies actually pass through one another. This suggests that the smaller companion actually dived deep, but off-center, through UGC 1810. The inner set of spiral arms is highly warped out of the plane with one of the arms going behind the bulge and coming back out the other side. How these two spiral patterns connect is still not precisely known. A possible mini-spiral may be visible in the spiral arms of UGC 1810 to the upper right. It is noticeable how the outermost spiral arm changes character as it passes this third galaxy, from smooth with lots of old stars (reddish in color) on one side to clumpy and extremely blue on the other. The fairly regular spacing of the blue star-forming knots fits with what is seen in the spiral arms of other galaxies and is predictable based on instabilities in the gas contained within the arm. The larger galaxy in the UGC 1810 - UGC 1813 pair has a mass that is about five times that of the smaller galaxy. In unequal pairs such as this, the relatively rapid passage of a companion galaxy produces the lopsided or asymmetric structure in the main spiral. Also in such encounters, the starburst activity typically begins in the minor galaxies earlier than in the major galaxies. These effects could be due to the fact that the smaller galaxies have consumed less of the gas present in their nucleus, from which new stars are born. Arp 273 lies in the constellation Andromeda and is roughly 300 million light-years away from Earth. The image shows a tenuous tidal bridge of material between the two galaxies that are separated by tens of thousands of light-years from each other. The interaction was imaged on December 17, 2010, with Hubble's Wide Field Camera 3 (WFC3). This Hubble image is a composite of data taken with three separate filters on WFC3 that allow a broad range of wavelengths covering the ultraviolet, blue, and red portions of the spectrum. *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/heic1107a.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2011/11/image/a/)*
37nov-26-2012
Pac-Man Moons of Saturn ----------------------- Scientists with NASA's Cassini mission have spotted two features shaped like the 1980s video game icon "Pac-Man" on moons of Saturn. One was observed on the moon Mimas in 2010 and the latest was observed on the moon Tethys. The pattern appears in thermal data obtained by Cassini's composite infrared spectrometer, with warmer areas making up the Pac-Man shape. Scientists saw the Tethys Pac-Man in data obtained on Sept. 14, 2011, where daytime temperatures inside the mouth of Pac-Man were seen to be cooler than their surroundings by 29 degrees Fahrenheit (15 kelvins). The warmest temperature recorded was a chilly minus 300 degrees Fahrenheit (90 kelvins). The Mimas Pac-Man was seen in data from Feb. 13, 2010. (For more information, see PIA12867.) The high temperature at Tethys is actually slightly cooler than the warmest temperature at Mimas (about minus 290 degrees Fahrenheit or 95 kelvins). One version of the image pegs white to be the hottest temperatures on both moons - minus 290 degrees Fahrenheit (95 kelvins) on Mimas and minus 300 degrees Fahrenheit (90 kelvins) on Tethys. Another version shows the minus 290 degrees Fahrenheit (95 kelvins) as white on both moons, revealing a subtler temperature variation on Tethys. At Tethys, unlike Mimas, the Pac-Man pattern can also be seen subtly in visible-light images of the surface, as a dark lens-shaped region. This brightness variation was first noticed in an image from NASA's Voyager spacecraft in 1980. Scientists theorize that the Pac-Man thermal shape on the Saturnian moons occurs because high-energy electrons bombard low latitudes on the side of the moon that faces forward as it orbits around Saturn, turning a fluffy surface into hard-packed ice. As a result, the altered surface does not heat as rapidly in the sunshine or cool down as quickly at night as the rest of the surface, similar to how a boardwalk at the beach feels cooler during the day but warmer at night than the nearby sand. Finding another PacMan on Tethys confirms that high-energy electrons can dramatically alter the surface of an icy moon. Also, because the altered region on Tethys, unlike on Mimas, is also bombarded by icy particles from Enceladus' plumes, it implies the surface alteration is occurring more quickly than its recoating by plume particles. *Image: NASA/JPL-Caltech/GSFC/SWRI \[[high-resolution](http://www.nasa.gov/images/content/708472main_pia16198-43_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/cassini/multimedia/pia16198.html)*
Chandra X-ray Observatory Center38nov-25-2012
All-Wavelengths Galactic Center ------------------------------- In celebration of the International Year of Astronomy 2009, NASA's Great Observatories -- the Hubble Space Telescope, the Spitzer Space Telescope, and the Chandra X-ray Observatory -- have collaborated to produce an unprecedented image of the central region of our Milky Way galaxy. In this spectacular image, observations using infrared light and X-ray light see through the obscuring dust and reveal the intense activity near the galactic core. Note that the center of the galaxy is located within the bright white region to the right of and just below the middle of the image (labeled Sagitarrius A when you roll your mouse over the above composite image). The entire image width covers about one-half a degree, about the same angular width as the full moon. Each telescope's contribution is presented in a different color: Yellow represents the near-infrared observations of Hubble. They outline the energetic regions where stars are being born as well as reveal hundreds of thousands of stars. Red represents the infrared observations of Spitzer. The radiation and winds from stars create glowing dust clouds that exhibit complex structures from compact, spherical globules to long, stringy filaments. Blue and violet represents the X-ray observations of Chandra. X-rays are emitted by gas heated to millions of degrees by stellar explosions and by outflows from the supermassive black hole in the galaxy's center. The bright blue blob on the left side of the full field image is emission from a double star system containing either a neutron star or a black hole. When these views are brought together, this composite image provides one of the most detailed views ever of our galaxy's mysterious core. *Image: X-ray: NASA/CXC/UMass/D. Wang et al.; Optical: NASA/ESA/STScI/D.Wang et al.; IR: NASA/JPL-Caltech/SSC/S.Stolovy \[[high-resolution](http://chandra.harvard.edu/photo/2009/galactic/galactic.jpg)\]* *Caption: [Chandra space telescope](http://chandra.harvard.edu/photo/2009/galactic/)*
S. Deiries/ESO39nov-24-2012
Comet's McNaught Spectacular ---------------------------- Comet McNaught setting behind Mount Paranal, in January 2007. *Image: S. Deiries/ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/mc_naught42.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/mc_naught42/)*
40nov-23-2012
Celestial Finger Painting ------------------------- This colour-composite image was obtained by FORS1 on ANTU. It displays a sky area near the Chamaeleon I complex of bright nebulae and hot stars in the constellation of the same name, close to the southern celestial pole.This picture was taken a few days before the Paranal Inauguration and the "hand-over" to the astronomers on April 1, 1999.This colour composite photo of the Chamaeleon I area is based on six 1-min exposures obtained with VLT UT1 + FORS1 in the V, R and I bands. The sky field measures 6.8 x 11.2 arcmin2; North is up and East is left. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso9921c.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso9921c/)*
41nov-22-2012
Winter Dunes on Mars -------------------- Dunes within a crater on Mars are visible in this image. This crater is located in the Southern hemisphere where it was winter at the time this image was taken. This observation documents new seasonal processes occurring on dunes at this latitude, as well as other interesting phenomena. The bright tones are interpreted as carbon dioxide or water frost. This is generally concentrated on the east-facing slopes of the dunes, which are in shadow and therefore cooler. Some dark spots on the dunes may be areas that have defrosted more than surrounding terrain. Landslides and dark-toned streaks are seen on many of the west-facing dune slopes. The general dune morphology indicates formation by westerly winds. However, zooming in on the image shows smaller scale ripples that appear to have been formed by winds blowing from the south and north. *Image: ESA/Hubble & NASA \[[high-resolution](NASA/JPL/University of Arizona)\]* *Caption: [Nathan Bridges & Kelly Kolb](http://hirise.lpl.arizona.edu/PSP_001558_1325)*
42nov-21-2012
Loose Spiral Galaxy ------------------- The NASA/ESA Hubble Space Telescope has spotted the spiral galaxy ESO 499-G37, seen here against a backdrop of distant galaxies, scattered with nearby stars. The galaxy is viewed from an angle, allowing Hubble to reveal its spiral nature clearly. The faint, loose spiral arms can be distinguished as bluish features swirling around the galaxy’s nucleus. This blue tinge emanates from the hot, young stars located in the spiral arms. The arms of a spiral galaxy have large amounts of gas and dust, and are often areas where new stars are constantly forming. The galaxy’s most characteristic feature is a bright elongated nucleus. The bulging central core usually contains the highest density of stars in the galaxy, where typically a large group of comparatively cool old stars are packed in this compact, spheroidal region. One feature common to many spiral galaxies is the presence of a bar running across the centre of the galaxy. These bars are thought to act as a mechanism that channels gas from the spiral arms to the centre, enhancing the star formation. Recent studies suggest that ESO 499-G37’s nucleus sits within a small bar up to a few hundreds of light-years along, about a tenth the size of a typical galactic bar. Astronomers think that such small bars could be important in the formation of galactic bulges since they might provide a mechanism for bringing material from the outer regions down to the inner ones. However, the connection between bars and bulge formation is still not clear since bars are not a universal feature in spiral galaxies. Lying in the constellation of Hydra, ESO 499-G37 is located about 59 million light-years away from the Sun. The galaxy belongs to the NGC 3175 group. ESO 499-G37 was first observed in the late seventies within the ESO/Uppsala Survey of the ESO (B) atlas. This was a joint project undertaken by the European Southern Observatory (ESO) and the Uppsala Observatory, which used the ESO 1-metre Schmidt telescope at La Silla Observatory, Chile, to map a large portion of the southern sky looking for stars, galaxies, clusters, and planetary nebulae. This picture was created from visible and infrared exposures taken with the Wide Field Channel of the Advanced Camera for Surveys. The field of view is approximately 3.4 arcminutes wide. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1247a.jpg)\]* *Caption: [NASA/ESA](http://www.spacetelescope.org/images/potw1247a/)*
43nov-20-2012
Galactic Gas Bridge ------------------- ESA’s Planck space telescope has made the first conclusive detection of a bridge of hot gas connecting a pair of galaxy clusters across 10 million light-years of intergalactic space. Planck’s primary task is to capture the most ancient light of the cosmos, the Cosmic Microwave Background, or CMB. As this faint light traverses the Universe, it encounters different types of structure including galaxies and galaxy clusters – assemblies of hundreds to thousands of galaxies bound together by gravity. If the CMB light interacts with the hot gas permeating these huge cosmic structures, its energy distribution is modified in a characteristic way, a phenomenon known as the Sunyaev–Zel’dovich (SZ) effect, after the scientists who discovered it. This effect has already been used by Planck to detect galaxy clusters themselves, but it also provides a way to detect faint filaments of gas that might connect one cluster to another. In the early Universe, filaments of gaseous matter pervaded the cosmos in a giant web, with clusters eventually forming in the densest nodes. Much of this tenuous, filamentary gas remains undetected, but astronomers expect that it could most likely be found between interacting galaxy clusters, where the filaments are compressed and heated up, making them easier to spot. Planck’s discovery of a bridge of hot gas connecting the clusters Abell 399 and Abell 401, each containing hundreds of galaxies, represents one such opportunity. The presence of hot gas between the billion-light-year-distant clusters was first hinted at in X-ray data from ESA’s XMM-Newton, and the new Planck data confirm the observation. It also marks Planck’s first detection of inter-cluster gas using the SZ effect technique. By combining the Planck data with archival X-ray observations from the German satellite Rosat, the temperature of the gas in the bridge is found to be similar to the temperature of the gas in the two clusters – on the order of 80 million degrees Celsius. Early analysis suggests the gas could be mixture of the elusive filaments of the cosmic web mixed with gas originating from the clusters. A more detailed analysis and the possible detection of gas bridges connecting other clusters will help to provide a more conclusive answer. The new finding highlights the ability of Planck to probe galaxy clusters to their outskirts and beyond, examining their connection with the gas that permeates the entire Universe and from which all groups of galaxies formed. *Image: Sunyaev–Zel’dovich effect: ESA Planck Collaboration; optical image: STScI Digitized Sky Survey \[[high-resolution](http://www.esa.int/images/Planck_A399_A401_SZE_optical_H1.jpg)\]* *Caption: [ESA](http://www.esa.int/SPECIALS/Planck/SEMRT791M9H_0.html)*
44nov-19-2012
Mercury's Pie Crust Craters --------------------------- MESSENGER has discovered assemblages of tectonic landforms unlike any previously found on Mercury or elsewhere in the Solar System. The findings are reported in a paper led by Smithsonian scientist Thomas Watters, "Extension and contraction within volcanically buried impact craters and basins on Mercury," published in the December issue of the journal Geology. The surface of Mercury is covered with deformational landforms that formed by faulting in response to horizontal contraction or shortening as the planet's interior cooled and surface area shrank, causing blocks of crustal material to be pushed together. Contraction from cooling of Mercury's interior has been so dominant that extensional landforms caused by fault formation in response to horizontal stretching and pulling apart of crustal material had not been previously documented outside of the interiors of a few large impact basins. The MESSENGER spacecraft, in orbit around Mercury since March of last year, has revealed families of extensional troughs, or graben, that are encircled by contractional wrinkle ridges arranged in circular rings. The troughs can form complex patterns varying from the outlines of polygons inside the ridge rings to arcs that parallel the bounding ridges. "The pattern of winkle ridges and graben resembles the raised edge and cracks in a pie crust," said Watters of the Center for Earth and Planetary Studies at the National Air and Space Museum. The "pie crust" analogy also fits another notable aspect of these collections of tectonic landforms -- their association with "ghost" craters. Ghost craters are impact craters that have been flooded and buried by lava flows. The thin volcanic deposits overlying the rim of a fully buried impact crater serve to concentrate contractional forces, leading to the formation of a ridge ring that reveals the outline of the buried crater. "The special arrangement of the wrinkle ridges and graben in many of the ghost craters on Mercury is due to a combination of extensional forces from cooling and contraction of unusually thick lava flow units and contractional forces from cooling and contraction of the planet's interior," says Sean Solomon of the Columbia University's Lamont-Doherty Earth Observatory, coauthor and principal investigator of the MESSENGER mission. The eruption and rapid accumulation of very fluid lava flows into thick cooling units on a planet undergoing a high rate of global contraction may be why these systems of tectonic landforms in ghost craters on Mercury have not been seen elsewhere in the Solar System. *Image: NASA/The Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington/Smithsonian Institution \[[high-resolution](http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/Watters_Press_photo_1.jpeg)\]* *Caption: [Mercury Messenger Team](http://messenger.jhuapl.edu/news_room/details.php?id=231)*
45nov-18-2012
Planetary Nebula Reborn ----------------------- These images of the planetary nebula Abell 30 show one of the clearest views ever obtained of a special phase of evolution for these objects. The inset image on the right is a close-up view of A30 showing X-ray data from NASA's Chandra X-ray Observatory in purple and Hubble Space Telescope data showing optical emission from oxygen ions in orange. On the left is a larger view showing optical and X-ray data from the Kitt Peak National Observatory and ESA's XMM-Newton, respectively. In this image the optical data show emission from oxygen (orange) and hydrogen (green and blue), and X-ray emission is colored purple. A planetary nebula -- so called because it looks like a planet when viewed with a small telescope -- is formed in the late stage of the evolution of a sun-like star. After having steadily produced energy for several billion years through the nuclear fusion of hydrogen into helium in its central region, or core, the star undergoes a series of energy crises related to the depletion of hydrogen and subsequent contraction of the core. These crises culminate in the star expanding a hundred-fold to become a red giant. Eventually the outer envelope of the red giant is ejected and moves away from the star at a relatively sedate speed of less than 100,000 miles per hour. The star meanwhile is transformed from a cool giant into a hot, compact star that produces intense ultraviolet radiation and a fast wind of particles moving at about 6 million miles per hour. The interaction of the UV radiation and the fast wind with the ejected red giant envelope creates the planetary nebula, shown by the large spherical shell in the bigger image. In rare cases, nuclear fusion reactions in the region surrounding the star's core heat the outer envelope of the star so much that it temporarily becomes a red giant again. The sequence of events -- envelope ejection followed by a fast stellar wind -- is repeated on a much faster scale than before, and a small-scale planetary nebula is created inside the original one. In a sense, the planetary nebula is reborn. *Image: NASA/ESA \[[high-resolution](http://www.nasa.gov/images/content/707291main_8187689009_12a0086110_o_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2395.html)*
46nov-17-2012
Dry Ice Spiders of Mars ----------------------- Have you ever played with dry ice (with leather gloves on of course!)? Perhaps you've made Halloween punch? Set a spooky scene? The fun comes from the fact that dry ice goes directly from solid to vapor, unlike water ice which melts into liquid when it gets warm. On Mars the seasonal polar caps are composed of dry ice (carbon dioxide). In the springtime as the sun shines on the ice, it turns from solid to gas and causes erosion of the surface. I enjoy the incredible diversity of forms that the erosion takes, and am studying the factors that give us "spiders", "caterpillars", or "starbursts", all colloquial words for what we rigorously name "araneiform" terrain. This particular example shows eroded channels filled with bright ice, in contrast to the muted red of the underlying ground. In the summer the ice will disappear into the atmosphere, and we will see just the channels of ghostly spiders carved in the surface. This is truly Martian terrain - this type of erosion does not take place anywhere naturally on earth because our climate is too warm. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2560/ESP_020914_0930.jpg)\]* *Caption: [Candy Hansen/HiRISE](http://hirise.lpl.arizona.edu/ESP_020914_0930)*
47nov-16-2012
Stellar Stellar Cluster ----------------------- Like a July 4 fireworks display, a young, glittering collection of stars looks like an aerial burst. The cluster is surrounded by clouds of interstellar gas and dust—the raw material for new star formation. The nebula, located 20,000 light-years away in the constellation Carina, contains a central cluster of huge, hot stars, called NGC 3603. This environment is not as peaceful as it looks. Ultraviolet radiation and violent stellar winds have blown out an enormous cavity in the gas and dust enveloping the cluster, providing an unobstructed view of the cluster. Most of the stars in the cluster were born around the same time but differ in size, mass, temperature, and color. The course of a star's life is determined by its mass, so a cluster of a given age will contain stars in various stages of their lives, giving an opportunity for detailed analyses of stellar life cycles. NGC 3603 also contains some of the most massive stars known. These huge stars live fast and die young, burning through their hydrogen fuel quickly and ultimately ending their lives in supernova explosions. Star clusters like NGC 3603 provide important clues to understanding the origin of massive star formation in the early, distant universe. Astronomers also use massive clusters to study distant starbursts that occur when galaxies collide, igniting a flurry of star formation. The proximity of NGC 3603 makes it an excellent lab for studying such distant and momentous events. This Hubble Space Telescope image was captured in August 2009 and December 2009 with the Wide Field Camera 3 in both visible and infrared light, which trace the glow of sulfur, hydrogen, and iron. *Image: NASA, ESA, R. O'Connell (University of Virginia), F. Paresce (National Institute for Astrophysics, Bologna, Italy), E. Young (Universities Space Research Association/Ames Research Center), the WFC3 Science Oversight Committee, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2010-22-a-print.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2010/22/image/a/)*
48nov-15-2012
Supernova Death and New Life ---------------------------- Supernova remnant W44 is the focus of this new image created by combining data from ESA’s Herschel and XMM-Newton space observatories. W44 is the vast purple sphere that dominates the left hand side of this image, and measures about 100 light-years across. XMM-Newton data reveal that the remnant is filled with X-ray emission from extremely hot gas. Herschel’s three-colour infrared view comprises PACS 70 and 160 micron and SPIRE 250 micron images. X-ray data from XMM-Newton’s EPIC instrument for W44 only has been added in light and dark blue to represent high- (2–8 keV) and low-energy (1.2–2 keV) X-ray emission, respectively. The field of view is about 1º across. North is towards the bottom left of the image; east is to the top right. *Image: Herschel: Q. Nguyen Luong & F. Motte, HOBYS Key Program consortium, Herschel SPIRE/PACS/ESA consortia. XMM-Newton: ESA/XMM-Newton \[[high-resolution](http://www.esa.int/images/w44_HERSCHEL_XMM_H3.jpg)\]* *Caption: [ESA](http://www.esa.int/esaSC/SEMNPE72Q8H_index_1.html)*
49nov-14-2012
Map of Tethys ------------- This global map of Saturn's moon Tethys was created using images taken during Cassini spacecraft flybys. The map is an equidistant (simple cylindrical) projection and has a scale of 293 meters (960 feet) per pixel at the equator in the full size version. The mean radius of Tethys used for projection of this map is 536.3 kilometers (333.2 miles). The resolution of the map is 32 pixels per degree. *Image: NASA/JPL/Space Science Institute \[[high-resolution](http://www.ciclops.org/view/7421/Map_of_Tethys_-_June_2012?js=1)\]* *Caption: NASA/JPL/Space Science Institute*
50nov-13-2012
Firefly Galaxies ---------------- Luminous galaxies glow like fireflies on a dark night in this image snapped by the NASA/ESA Hubble Space Telescope. The central galaxy in this image is a gigantic elliptical galaxy designated 4C 73.08. A prominent spiral galaxy seen from "above" shines in the lower part of the image, while examples of galaxies viewed edge-on also populate the cosmic landscape. In the optical and near-infrared light captured to make this image, 4C 73.08 does not appear all that beastly. But when viewed in longer wavelengths the galaxy takes on a very different appearance. Dust-piercing radio waves reveal plumes emanating from the core, where a supermassive black hole spews out twin jets of material. 4C 73.08 is classified as a radio galaxy as a result of this characteristic activity in the radio part of the electromagnetic spectrum. Astronomers must study objects such as 4C 73.08 in multiple wavelengths in order to learn their true natures, just as seeing a firefly’s glow would tell a scientist only so much about the insect. Observing 4C 73.08 in visible light with Hubble illuminates galactic structure as well as the ages of constituent stars, and therefore the age of the galaxy itself. 4C 73.08 is decidedly redder than the prominent, bluer spiral galaxy in this image. The elliptical galaxy’s redness comes from the presence of many older, crimson stars, which shows that 4C 73.08 is older than its spiral neighbour. The image was taken using Hubble’s Wide Field Camera 3 through two filters: one which captures green light, and one which captures red and near-infrared light. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1246a.jpg)\]* *Caption: [Hubble Heritage Team](http://www.spacetelescope.org/images/potw1246a/)*
51nov-12-2012
Titan Vortex ------------ Titan's swirling south-polar vortex stands out brightly against the other clouds of the south pole. Cassini is monitoring the development of the south polar vortex to help understand seasonal changes on Saturn's largest moon. For a color image of the south polar vortex on Titan, see [PIA14919](http://www.ciclops.org/view.php?id=7235). For a movie of the vortex, see [PIA14920](http://www.ciclops.org/view.php?id=7236). This view looks toward the trailing hemisphere of Titan (3200 miles, 5150 kilometers across). North on Titan is up and rotated 36 degrees to the left. The image was taken with the Cassini spacecraft narrow-angle camera on Aug. 31, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 938 nanometers. The view was acquired at a distance of approximately 750,000 miles (1.2 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 74 degrees. Image scale is 4 miles (7 kilometers) per pixel. *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://www.ciclops.org/view_media/36816/Seasonal_Swirl)\]* *Caption: [Cassini Solstice Team](http://www.ciclops.org/view/7350/Seasonal_Swirl?js=1)*
52nov-11-2012
Jupiter's Spots --------------- In what's beginning to look like a case of planetary measles, a third red spot has appeared alongside its cousins — the Great Red Spot and Red Spot Jr. — in the turbulent Jovian atmosphere. This third red spot, which is a fraction of the size of the two other features, lies to the west of the Great Red Spot in the same latitude band of clouds. The new red spot was previously a white oval-shaped storm. The change to a red color indicates its swirling storm clouds are rising to heights like the clouds of the Great Red Spot. One possible explanation is that the red storm is so powerful it dredges material from deep beneath Jupiter's cloud tops and lifts it to higher altitudes where solar ultraviolet radiation — via some unknown chemical reaction — produces the familiar brick color. Detailed analysis of the visible-light images taken by Hubble's Wide Field Planetary Camera 2 on May 9 and 10, and near-infrared adaptive optics images taken by the W.M. Keck telescope on May 11, is revealing the relative altitudes of the cloud tops of the three red ovals. Because all three oval storms are bright in near-infrared light, they must be towering above the methane in Jupiter's atmosphere, which absorbs the Sun's infrared light and so looks dark in infrared images. Turbulence and storms first observed on Jupiter more than two years ago are still raging, as revealed in the latest pictures. The Hubble and Keck images also reveal the change from a rather bland, quiescent band surrounding the Great Red Spot just over a year ago to one of incredible turbulence on both sides of the spot. Red Spot Jr. appeared in spring of 2006. The Great Red Spot has persisted for as long as 200 to 350 years, based on early telescopic observations. If the new red spot and the Great Red Spot continue on their courses, they will encounter each other in August, and the small oval will either be absorbed or repelled from the Great Red Spot. Red Spot Jr. which lies between the two other spots, and is at a lower latitude, will pass the Great Red Spot in June. The Hubble and Keck images may support the idea that Jupiter is in the midst of global climate change, as first proposed in 2004 by Phil Marcus, a professor of mechanical engineering at the University of California, Berkeley. The planet's temperatures may be changing by 15 to 20 degrees Fahrenheit. The giant planet is getting warmer near the equator and cooler near the South Pole. He predicted that large changes would start in the southern hemisphere around 2006, causing the jet streams to become unstable and spawn new vortices. *Image and Caption: M. Wong and I. de Pater (University of California, Berkeley) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2008-23-a-full_jpg.jpg)\]*
53nov-10-2012
Part of the Tarantula Nebula ---------------------------- One square degree image of the Tarantula Nebula and its surroundings. The spidery nebula is seen in the upper-centre of the image. Slightly to the lower-right, a web of filaments harbours the famous supernova SN 1987A (see below). Many other reddish nebulae are visible in the image, as well as a cluster of young stars on the left, known as NGC 2100. Technical information: the image is based on observations carried out by Joao Alves (Calar Alto, Spain), Benoit Vandame and Yuri Beletski (ESO) with the Wide Field Imager (WFI) at the 2.2-m telescope on La Silla. These data consist of a 2x2 WFI mosaic in the B- and V-bands, and in the H-alpha and \[OIII\] narrow bands. The data were first processed with the ESO/MVM pipeline by the Advanced Data Products (ADP) group at ESO. *Image: ESO/R. Fosbury (ST-ECF) \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso0650a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0650a/)*
54nov-9-2012
Nearby Cradle ------------- The Milky Way and other galaxies in the universe harbor many young star clusters and associations that each contain hundreds to thousands of hot, massive, young stars known as O and B stars. The star cluster Cygnus OB2 contains more than 60 O-type stars and about a thousand B-type stars. Deep observations with NASA’s Chandra X-ray Observatory have been used to detect the X-ray emission from the hot outer atmospheres, or coronas, of young stars in the cluster and to probe how these fascinating star factories form and evolve. About 1,700 X-ray sources were detected, including about 1,450 thought to be stars in the cluster. In this image, X-rays from Chandra (blue) have been combined with infrared data from NASA’s Spitzer Space Telescope (red) and optical data from the Isaac Newton Telescope (orange). *Image: NASA \[[high-resolution](http://www.nasa.gov/images/content/705606main_chandra_cygnus_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2391.html)*
ESO/H. Boffin55nov-8-2012
White Dwarf Dance ----------------- Astronomers using ESO’s Very Large Telescope have discovered a pair of stars orbiting each other at the centre of one of the most remarkable examples of a planetary nebula. The new result confirms a long-debated theory about what controls the spectacular and symmetric appearance of the material flung out into space. The results are published in the 9 November 2012 issue of the journal Science. Planetary nebulae are glowing shells of gas around white dwarfs — Sun-like stars in the final stages of their lives. Fleming 1 is a beautiful example that has strikingly symmetric jets that weave into knotty, curved patterns. It is located in the southern constellation of Centaurus (The Centaur) and was discovered just over a century ago by Williamina Fleming, a former maid who was hired by Harvard College Observatory after showing an aptitude for astronomy. Astronomers have long debated how these symmetric jets could be created, but no consensus has been reached. Now, a research team led by Henri Boffin (ESO, Chile) has combined new Very Large Telescope (VLT) observations of Fleming 1 with existing computer modelling to explain in detail for the first time how these bizarre shapes came about. The team used ESO’s VLT to study the light coming from the central star. They found that Fleming 1 is likely to have not one but two white dwarfs at its centre, circling each other every 1.2 days. Although binary stars have been found at the hearts of planetary nebulae before, systems with two white dwarfs orbiting each other are very rare. “The origin of the beautiful and intricate shapes of Fleming 1 and similar objects has been controversial for many decades,” says Henri Boffin. “Astronomers have suggested a binary star before, but it was always thought that in this case the pair would be well separated, with an orbital period of tens of years or longer. Thanks to our models and observations, which let us examine this unusual system in great detail and peer right into the heart of the nebula, we found the pair to be several thousand times closer.” When a star with a mass up to eight times that of the Sun approaches the end of its life, it blows off its outer shells and begins to lose mass. This allows the hot, inner core of the star to radiate strongly, causing this outward-moving cocoon of gas to glow brightly as a planetary nebula. While stars are spherical, many of these planetary nebulae are strikingly complex, with knots, filaments, and intense jets of material forming intricate patterns. Some of the most spectacular nebulae — including Fleming 1 — present point-symmetric structures. For this planetary nebula it means that the material appears to shoot from both poles of the central region in S-shaped flows. This new study shows that these patterns for Fleming 1 are the result of the close interaction between a pair of stars — the surprising swansong of a stellar couple. “This is the most comprehensive case yet of a binary central star for which simulations have correctly predicted how it shaped the surrounding nebula — and in a truly spectacular fashion,” explains co-author Brent Miszalski, from SAAO and SALT (South Africa). The pair of stars in the middle of this nebula is vital to explain its observed structure. As the stars aged, they expanded, and for part of this time, one acted as a stellar vampire, sucking material from its companion. This material then flowed in towards the vampire, encircling it with a disc known as an accretion disc. As the two stars orbited one another, they both interacted with this disc and caused it to behave like a wobbling spinning top — a type of motion called precession. This movement affects the behaviour of any material that has been pushed outwards from the poles of the system, such as outflowing jets. This study now confirms that precessing accretion discs within binary systems cause the stunningly symmetric patterns around planetary nebulae like Fleming 1. The deep images from the VLT have also led to the discovery of a knotted ring of material within the inner nebula. Such a ring of material is also known to exist in other families of binary systems, and appears to be a telltale signature of the presence of a stellar couple. “Our results bring further confirmation of the role played by interaction between pairs of stars to shape, and perhaps even form, planetary nebulae,” concludes Boffin. *Image: ESO/H. Boffin \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1244a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/news/eso1244/)*
56nov-7-2012
Smiley Crater ------------- It looks like even the craters on Mercury have heard of Bob Ross! The central peaks of this complex crater have formed in such a way that it resembles a smiling face. This image is oriented so north is toward the bottom. This image was acquired as a high-resolution targeted observation. Targeted observations are images of a small area on Mercury's surface at resolutions much higher than the 200-meter/pixel morphology base map. It is not possible to cover all of Mercury's surface at this high resolution, but typically several areas of high scientific interest are imaged in this mode each week. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EN0258976725M.nomap.jpg)\]* *Caption: [Mercury Messenger Team](http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=997)*
57nov-6-2012
Black Hole Lobes ---------------- The radio source Cygnus A is produced in a galaxy some 600 million light-years away. The radio waves are coming from electrons propelled at nearly the speed of light through a long, thin "jet" at the core of the galaxy and deposited in giant "radio lobes." It is here where the speeding electrons are trapped by the magnetic field around the galaxy to produce radio waves much like the Van Allen radiation belts around the Earth. Where did all the electrons come from? From the bright, small radio component in the center of the galaxy -- the location of a black hole. *Image: Image courtesy of NRAO/AUI. Image courtesy of NRAO/AUI \[[high-resolution](http://images.nrao.edu/images/CygA-YellowOrange_hi.tif)\]* *Caption: [NRAO](http://images.nrao.edu/110)*
Brad Goldpaint58nov-5-2012
Gorgeous Aurora Over Oregon --------------------------- "It's not every day you see the aurora in Central Oregon," wrote photographer [Brad Goldpaint](http://goldpaintphotography.com/) to Wired regarding his incredible shot of heavenly phenomenon. That is certainly true. Auroras are created when energetic particles flowing from the sun interact with the Earth's upper atmosphere, creating a cascading shower of light with brilliant green, blue, and purple hues. They can typically only be found over the most northern and southern extremes of our planet. Aurora are strongest after a solar energetic particle event, such as a flare, when the sun releases a huge burst of energy and ions. Such an event happened on July 12, 2012, when the sun produced an X-class flare -- the strongest type of flare. Goldpaint knew that this tremendous solar explosion was going to increase the chances of spotting auroras as far south as Central Oregon and he grabbed his camera. On his [website's blog](http://goldpaintphotography.com/2012/11/01/inplainsight/), Goldpaint wrote about how he went out to "an area with very little light pollution, a clear view of the night sky facing north, and cross my fingers." Arriving just after sunset, his camera started picking up a faint, pink glow on the horizon. Soon, bursting auroras were coming over the distant mountains. Using long exposures, he was able to capture far more than the human eye can discern. "The magnitude of colors and lights were like I’ve never seen before," he wrote. Goldpaint wrote: "By 2:30am, my efforts and dedication began paying off. The sky exploded!!! A large, thick band of light burst out of nowhere just behind South Sister and slowly drifted all the way to Broken Top and beyond. Immediately after words, the entire sky filled with thin bands of light. I could barely make them out with my own eyes, but my camera picked them up perfectly. The majority of light bands lasted until 3:30am, just as the sun began to rise." "This was by far one of the most unforgettable experiences I’ve ever witnessed and feel this is why I’m so drawn to photography. However, for me, it’s not just about getting the shot, although it was a plus, it’s about escaping my comfort zone and challenging myself to experience something entirely new. I often hear about people who are scared of the dark and would never think about doing what I do. Would you believe me if I said I was afraid of the dark too? Every time I’m out there I get a good scare from a sound I don’t recognize. I believe it’s about conquering one’s fears and allowing your eyes to become your guide." *Image: [Brad Goldpaint](http://goldpaintphotography.com/)* *Caption: [Brad Goldpaint/Wired Science](http://goldpaintphotography.com/2012/11/01/inplainsight/)*
59nov-4-2012
Dwarfed by Saturn ----------------- Saturn's moon Mimas appears near Saturn, dwarfed by its parent planet in this image. Mimas (246 miles, or 396 kilometers across) appears tiny compared to the storms clearly visible in far northern and southern hemispheres of Saturn. This view looks toward the unilluminated side of the rings from about 18 degrees below the ringplane. North on Saturn is up and rotated 27 degrees to the left. The image was taken with the Cassini spacecraft wide-angle camera on Aug. 20, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was acquired at a distance of approximately 1.5 million miles (2.4 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 64 degrees. Image scale is 87 miles (140 kilometers) per pixel. *Photo and Caption: NASA/JPL-Caltech/Space Science Institute. \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA14631.jpg)\]*
60nov-3-2012
Star Formation in LMC --------------------- This active region of star formation in the Large Magellanic Cloud (LMC), as photographed by NASA's Hubble Space Telescope, unveils wispy clouds of hydrogen and oxygen that swirl and mix with dust on a canvas of astronomical size. The LMC is a satellite galaxy of the Milky Way. This particular region within the LMC, referred to as N 180B, contains some of the brightest known star clusters. The hottest blue stars can be brighter than a million of our Suns. Their intense energy output generates not only harsh ultraviolet radiation but also incredibly strong stellar "winds" of high-speed, charged particles that blow into space. The ultraviolet radiation ionizes the interstellar gas and makes it glow, while the winds can disperse the interstellar gas across tens or hundreds of light-years. Both actions are evident in N 180B. Also visible etched against the glowing hydrogen and oxygen gases are 100 light-year-long dust streamers that run the length of the nebula, intersecting the core of the cluster near the center of the image. Perpendicular to the direction of the dark streamers, bright orange rims of compact dust clouds appear near the bottom right of and top left corners of the image. These dark concentrations are on the order of a few light-years in size. Also visible among the dust clouds are so-called "elephant trunk" stalks of dust. If the pressure from the nearby stellar winds is great enough to compress this material and cause it to gravitationally contract, star formation might be triggered in these small dust clouds. These dust clouds are evidence that this is still a young star-formation region. This image was taken with Hubble's Wide Field Planetary Camera 2 in 1998 using filters that isolate light emitted by hydrogen and oxygen gas. To create a color composite, the data from the hydrogen filter were colorized red, the oxygen filter were colorized blue, and a combination of the two filters averaged together was colorized green. The amalgamation yields pink and orange hydrogen clouds set amid a field of soft blue oxygen gas. Dense dust clouds block starlight and glowing gas from our view point. *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/2006/41/image/a/format/xlarge_web/)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2006/41/image/a/)*
Spitzer Space Telescope61nov-2-2012
Chaotic Star Birth ------------------ Located 1,000 light-years from Earth in the constellation Perseus, a reflection nebula called NGC 1333 epitomizes the beautiful chaos of a dense group of stars being born. Most of the visible light from the young stars in this region is obscured by the dense, dusty cloud in which they formed. With NASA's Spitzer Space Telescope, scientists can detect the infrared light from these objects. This allows a look through the dust to gain a more detailed understanding of how stars like our sun begin their lives. The young stars in NGC 1333 do not form a single cluster, but are split between two sub-groups. One group is to the north near the nebula shown as red in the image. The other group is south, where the features shown in yellow and green abound in the densest part of the natal gas cloud. With the sharp infrared eyes of Spitzer, scientists can detect and characterize the warm and dusty disks of material that surround forming stars. By looking for differences in the disk properties between the two subgroups, they hope to find hints of the star- and planet-formation history of this region. The knotty yellow-green features located in the lower portion of the image are glowing shock fronts where jets of material, spewed from extremely young embryonic stars, are plowing into the cold, dense gas nearby. The sheer number of separate jets that appear in this region is unprecedented. This leads scientists to believe that by stirring up the cold gas, the jets may contribute to the eventual dispersal of the gas cloud, preventing more stars from forming in NGC 1333. In contrast, the upper portion of the image is dominated by the infrared light from warm dust, shown as red. *Image: NASA/JPL-Caltech/R. A. Gutermuth (Harvard-Smithsonian CfA) \[[high-resolution](http://www.spitzer.caltech.edu/uploaded_files/images/0008/7129/ssc2005-24a.jpg)\]* *Caption: [Spitzer space telescope](http://www.spitzer.caltech.edu/images/1521-ssc2005-24a-Chaotic-Star-Birth)*
62nov-1-2012
Lightning on Saturn ------------------- These false-color mosaics from NASA's Cassini spacecraft capture lightning striking within the huge storm that encircled Saturn's northern hemisphere for much of 2011. The larger mosaic on the left of the panel shows the lightning flash, which appears as a blue dot. The smaller mosaic on the right is composed of images taken 30 minutes later, and the lightning is not flashing at that time. The white arrow in the annotated version of this panel points to the location where the lightning occurred in the clouds. The optical energy of this and other flashes on Saturn is comparable to the strongest of the flashes on Earth. The flash is approximately 120 miles (200 kilometers) in diameter when it exits the tops of the clouds. From this, scientists deduce that the lightning bolts originate in the clouds deeper down in Saturn's atmosphere where water droplets freeze. This is analogous to where lightning is created on Earth. This lightning flash appears only in the filter sensitive to blue visible light, and the images were enhanced to increase the visibility of the lightning. Images taken using red, green and blue spectral filters are usually combined to create a natural color view. Because visible red-light images were not available, images taken using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers were used in place of red. Also, the blue filter image was enhanced to increase the visibility of the lightning. The result is a type of false color image. The images were obtained with the Cassini spacecraft narrow-angle camera on March 6, 2011, at a distance of approximately 2 million miles (3.3 million kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 83 degrees. These mosaics are simple cylindrical map projections, defined such that a square pixel subtends equal intervals of latitude and longitude. At higher latitudes, the pixel size in the north-south direction remains the same, but the pixel size (in terms of physical extent on the planet) in the east-west direction becomes smaller. The pixel size is set at the equator, where the distances along the sides are equal. This map has a pixel size of 12 miles (20 kilometers) at the equator. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter and its two onboard cameras were designed, developed and assembled at JPL. The imaging operations center is based at the Space Science Institute in Boulder, Colo. *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA14921.jpg)\]* *Caption: [NASA](http://photojournal.jpl.nasa.gov/catalog/PIA14921)*
63oct-31-2012
The Ghost in Cephus ------------------- Described as a "dusty curtain" or "ghostly apparition," mysterious reflection nebula VdB 152 really is very faint. Far from your neighborhood on this Halloween Night, the cosmic phantom is nearly 1,400 light-years away. Also catalogued as Ced 201, it lies along the northern Milky Way in the royal constellation Cepheus. Near the edge of a large molecular cloud, pockets of interstellar dust in the region block light from background stars or scatter light from the embedded bright star giving parts of the nebula a characteristic blue color. Ultraviolet light from the star is also thought to cause a dim reddish luminescence in the nebular dust. Though stars do form in molecular clouds, this star seems to have only accidentally wandered into the area, as its measured velocity through space is very different from the cloud's velocity. This deep telescopic image of the region spans about 7 light-years. *Image: NASA/Stephen Leshin \[[high-resolution](http://www.nasa.gov/images/content/702193main_ghostly_image_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_gallery_2285.html)*
64oct-30-2012
Degas on Mercury ---------------- Though many craters are visible in this color view of Mercury's limb, Degas gets noticed. Located near the center of the image, the distinctive blue color of the low-reflectance material associated with Degas contrasts with the surrounding terrain and neighboring craters. View these previously posted web images to see Degas in high-resolution with the Narrow Angle Camera (NAC) or in high-resolution color with the WAC. This image was acquired as a targeted observation that occurred simultaneously with a measurement by the Mercury Atmospheric and Surface Composition Spectrometer (MASCS). Targeted observations that involve both MDIS and MASCS facilitate combining the data from both instruments to understand the color and reflectance of small-scale geologic features on Mercury's surface. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EW0258052721G.3band.nomap.ver2.png)\]* *Caption: [Mercury Messenger Team](http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=991)*
65oct-29-2012
Young and Old Stars ------------------- The NASA/ESA Hubble Space Telescope offers an impressive view of the centre of globular cluster NGC 6362. The image of this spherical collection of stars takes a deeper look at the core of the globular cluster, which contains a high concentration of stars with different colours. Tightly bound by gravity, globular clusters are composed of old stars, which, at around 10 billion years old, are much older than the Sun. These clusters are fairly common, with more than 150 currently known in our galaxy, the Milky Way, and more which have been spotted in other galaxies. Globular clusters are among the oldest structures in the Universe that are accessible to direct observational investigation, making them living fossils from the early years of the cosmos. Astronomers infer important properties of globular clusters by looking at the light from their constituent stars. For many years, they were regarded as ideal laboratories for testing the standard stellar evolution theory. Among other things, this theory suggests that most of the stars within a globular cluster should be of a similar age. Recently, however, high precision measurements performed in numerous globular clusters, primarily with the Hubble Space Telescope, has led some to question this widely accepted theory. In particular, certain stars appear younger and bluer than their companions, and they have been dubbed blue stragglers. NGC 6362 contains many of these stars. Since they are usually found in the core regions of clusters, where the concentration of stars is large, the most likely explanation for this unexpected population of objects seems to be that they could be either the result of stellar collisions or transfer of material between stars in binary systems. This influx of new material would heat up the star and make it appear younger than its neighbours. NGC 6362 is located about 25 000 light-years from Earth in the constellation of Ara (The Altar). British astronomer James Dunlop first observed this globular cluster on 30 June 1826. This image was created combining ultraviolet, visual and infrared images taken with the Wide Field Channel of the Advanced Camera for Surveys and the Wide Field Camera 3. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1244a.jpg)\]* *Caption: [NASA/ESA](http://www.spacetelescope.org/images/potw1244a/)*
ESO/APEX/DSS2/ SuperCosmos/ Deha66oct-28-2012
Colorful Bubble --------------- Colour composite image of RCW120. It reveals how an expanding bubble of ionised gas about ten light-years across is causing the surrounding material to collapse into dense clumps where new stars are then formed. The 870-micron submillimetre-wavelength data were taken with the LABOCA camera on the 12-m Atacama Pathfinder Experiment (APEX) telescope. Here, the submillimetre emission is shown as the blue clouds surrounding the reddish glow of the ionised gas (shown with data from the SuperCosmos H-alpha survey). The image also contains data from the Second Generation Digitized Sky Survey (I-band shown in blue, R-band shown in red). *Image and caption: ESO/APEX/DSS2/ SuperCosmos/ Deharveng(LAM)/ Zavagno(LAM) \[[high-resolution](http://www.eso.org/public/images/eso0840a/)\]*
67oct-27-2012
Family Portrait, Inside Out --------------------------- NASA's MESSENGER spacecraft has constructed the first portrait of our solar system by combining 34 images taken by the spacecraft’s Wide Angle Camera on Nov. 3 and 16, 2010. The mosaic, pieced together over a period of a few weeks, comprises all of the planets except for Uranus and Neptune, which were too faint to detect. On March 17, 2011, MESSENGER may become the first probe ever to orbit Mercury. Scientists hope orbital observations will provide new answers to how Earth-like planets, like Mercury, are assembled and evolve. *Image: NASA, Johns Hopkins University Applied Physics Laboratory, Carnegie Institution of Washington \[[high-resolution](http://www.nasa.gov/images/content/517613main_solar_system_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_1868.html)*
68oct-26-2012
Hubble's Crab Nebula -------------------- This is a mosaic image, one of the largest ever taken by NASA's Hubble Space Telescope of the Crab Nebula, a six-light-year-wide expanding remnant of a star's supernova explosion. Japanese and Chinese astronomers recorded this violent event nearly 1,000 years ago in 1054, as did, almost certainly, Native Americans. The orange filaments are the tattered remains of the star and consist mostly of hydrogen. The rapidly spinning neutron star embedded in the center of the nebula is the dynamo powering the nebula's eerie interior bluish glow. The blue light comes from electrons whirling at nearly the speed of light around magnetic field lines from the neutron star. The neutron star, like a lighthouse, ejects twin beams of radiation that appear to pulse 30 times a second due to the neutron star's rotation. A neutron star is the crushed ultra-dense core of the exploded star. The Crab Nebula derived its name from its appearance in a drawing made by Irish astronomer Lord Rosse in 1844, using a 36-inch telescope. When viewed by Hubble, as well as by large ground-based telescopes such as the European Southern Observatory's Very Large Telescope, the Crab Nebula takes on a more detailed appearance that yields clues into the spectacular demise of a star, 6,500 light-years away. The newly composed image was assembled from 24 individual Wide Field and Planetary Camera 2 exposures taken in October 1999, January 2000, and December 2000. The colors in the image indicate the different elements that were expelled during the explosion. Blue in the filaments in the outer part of the nebula represents neutral oxygen, green is singly-ionized sulfur, and red indicates doubly-ionized oxygen. *Image: NASA, ESA, J. Hester and A. Loll (Arizona State University) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2005-37-a-print.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2005/2005/37/image/a/)*
69oct-25-2012
Monster Galaxy Stirred-Up By Black Hole --------------------------------------- The giant elliptical galaxy in the center of this image, taken by NASA's Hubble Space Telescope, is the most massive and brightest member of the galaxy cluster Abell 2261. Spanning a little more than one million light-years, the galaxy is about 10 times the diameter of our Milky Way galaxy. The bloated galaxy is a member of an unusual class of galaxies with a diffuse core filled with a fog of starlight. Normally, astronomers would expect to see a concentrated peak of light around a central black hole. The Hubble observations revealed that the galaxy's puffy core, measuring about 10,000 light-years, is the largest yet seen. The observations present a mystery, and studies of this galaxy may provide insight into how black hole behavior may shape the cores of galaxies. Astronomers used Hubble's Advanced Camera for Surveys and Wide Field Camera 3 to measure the amount of starlight across the galaxy, dubbed A2261-BCG. Abell 2261 is located three billion light-years away. The observations were taken March to May 2011. The Abell 2261 cluster is part of a multi-wavelength survey called the Cluster Lensing And Supernova survey with Hubble (CLASH). *Image: NASA, ESA, M. Postman (STScI), T. Lauer (NOAO), and the CLASH team \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2012-24-a-print.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2012/24/full/)*
70oct-24-2012
Shoreline of Ancient Titan Sea ------------------------------ This image from NASA's Cassini spacecraft shows an ancient southern sea that used to sprawl out near the south pole of Saturn's moon Titan. In an annotated version, the red outline traces the ancient shoreline. Within this basin is the largest present-day lake in Titan's southern hemisphere, Ontario Lacus. Ontario Lacus appears black, indicating it is filled with liquid. This image was obtained by Cassini's radar instrument on July 2009 and January 2010. Several images have been stitched together. By analyzing these images, scientists estimate the ancient sea was possibly as large as 300 by 170 miles (475 by 280 kilometers) across and likely less than a few hundred feet (meters) deep. Ontario Lacus is about 80 by 235 kilometers across, and probably at least 30 feet (10 meters) deep at its center. Seas may have covered large parts of the southern hemisphere less than 50,000 years ago. Titan, Saturn’s largest moon, is the only place besides Earth in our solar system that hosts large open bodies of liquid. At the cold temperatures of Titan, about minus 290 degrees Fahrenheit (94 kelvins), that liquid is not water, but methane and ethane. Over one hundred lakes and three seas are seen at the north pole of Titan, while the south pole only has a few small lakes. Scientists have suggested that cycles analogous to Croll-Milankovich cycles on Earth cause long-term cyclic transfer of liquid hydrocarbons from pole to pole, with the north pole now containing the bulk of the liquids. Less than 50,000 years ago, the cycle would have been reversed, suggesting that the south polar region should contain remnants of southern seas. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. NASA's Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, DC. The Cassini orbiter was designed, developed and assembled at JPL. The radar instrument was built by JPL and the Italian Space Agency, working with team members from the United States and several European countries. *Image: NASA/JPL-Caltech/ASI/Proxemy Research \[[high-resolution](http://photojournal.jpl.nasa.gov/catalog/PIA16166)\]* *Caption: [Cassini Solstice Team](http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4649)*
71oct-23-2012
The Grand Valles ---------------- Valles Marineris, seen at an angle of 45 degrees to the surface in near-true colour and with four times vertical exaggeration. The image covers an area of 630 000 sq km with a ground resolution of 100 m per pixel. The digital terrain model was created from 20 individual HRSC orbits, and the colour data were generated from 12 orbit swaths. The largest portion of the canyon, which spans right across the image, is known as Melas Chasma. Candor Chasma is the connecting trough immediately to the north, with the small trough Ophir Chasma beyond. Hebes Chasma can be seen in the far top left of the image. *Image: ESA/DLR/FU Berlin (G. Neukum) \[[high-resolution](http://www.esa.int/images/valles_3d_H.jpg)\]* *Caption: [ESA](http://www.esa.int/esaSC/SEMAEO4S18H_index_1.html)*
72oct-22-2012
Irregular Starburst Galaxy -------------------------- The NASA/ESA Hubble Space Telescope has imaged the faint irregular galaxy NGC 3738, a starburst galaxy. The galaxy is in the midst of a violent episode of star formation, during which it is converting reservoirs of hydrogen gas harboured in the galaxy’s centre into stars. Hubble spots this gas glowing red around NGC 3738, one of the most distinctive signs of ongoing star formation. Lying in the constellation of Ursa Major (The Great Bear), NGC 3738 is located about 12 million light-years from the Sun, and belongs to the Messier 81 group of galaxies. This galaxy — first observed by astronomer William Herschel back in 1789 — is a nearby example of a blue compact dwarf, the faintest type of starburst galaxy. Blue compact dwarfs are small compared to large spiral galaxies — NGC 3738 is around 10 000 light-years across, just one tenth of the size of the Milky Way. This type of galaxy is blue in appearance by virtue of containing large clusters of hot, massive stars, which ionise the surrounding interstellar gas with their intense ultraviolet radiation. They are relatively faint and appear to be irregular in shape. Unlike spirals or elliptical galaxies, irregular galaxies do not have any distinctive features, such as a nuclear bulge or spiral arms. Rather, they are extremely chaotic in appearance. These galaxies are thought to resemble some of the earliest that formed in the Universe and may provide clues as to how stars appeared shortly after the Big Bang. This image was created by combining visual and infrared images taken with the Wide Field Channel of the Advanced Camera for Surveys aboard the Hubble Space Telescope. The field of view of the Wide Field Channel is approximately 3.4 by 3.4 arcminutes wide. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1243a.jpg)\]* *Caption: [Hubble Heritage Team](http://www.spacetelescope.org/images/potw1243a/)*
73oct-19-2012
One Galaxy Piercing the Heart of Another ---------------------------------------- *__When the lamp is shattered, The light in the dust lies dead. When the cloud is scattered, The rainbow's glory is shed.__* These words, which open Shelley’s poem "When the Lamp is Shattered," employ visions of nature to symbolize life in decay and rebirth. It's as if he had somehow foreseen the creation of this new Gemini Legacy image, and penned a caption for it. What Gemini has captured is nothing short of poetry in motion: the colorful and dramatic tale of a life-and-death struggle between two galaxies interacting. All the action appears in a single frame, with the stunning polar-ring galaxy NGC 660 as the focus of attention. Polar-ring galaxies are peculiar objects. Astronomers have found only a handful of them, so not much is known about their origins. Most have an early-type spiral system, called a lenticular galaxy, as the central showpiece. But NGC 660, which lies about 40 million light-years distant toward the direction of Pisces the Fishes, is the only polar-ring galaxy known with what is called a late-type lenticular galaxy as its host. All, however, display a ring of stars, dust, and gas that extends tens of thousands of light-years across space along an orbit nearly perpendicular to the main disk. Models of how polar-ring galaxies form offer two general formation scenarios: 1) a piercing merger between two galaxies aligned roughly at right angles, or 2) when the host galaxy tidally strips material from a passing gas-rich spiral and strews it into a ring. What you see in this new Gemini Legacy image, then, is not a single dynamic body but either the “bloody” aftermath of one galaxy piercing the heart of another or the remains of a furious tidal struggle between two galaxies that shattered one galaxy’s "lamp," scattered its dust and gas, and formed a colorful, 40,000-light-year-long ring of visual glory. ### Born of Violence Brian Svoboda of the University of Arizona, who recently studied the chemical and temperature environment of NGC 660, believes that unique morphology arises from a previous interaction with a gas-rich galaxy. The geometry of NGC 660 –– an enormous edge-on polar ring (some 40,000 light-years across) –– contains more gas (and associated star formation) than its host, which strongly suggests a violent formation. "One of the main characteristics of NGC 660 is that the ring is not truly polar, but is inclined ~45 degrees from the plane of the disk,” Svoboda points out. “The simulations for the piercing mergers cannot reproduce these low inclination polar rings; however, the tidal accretion scenario can." NGC 660’s polar ring resolves into hundreds of objects, a considerable part of which are blue and red supergiant stars. The youngest detected stars in the ring formed only about 7 million years ago, indicating a long, ongoing process. "Gemini's incredible definition of the active star forming regions strewn through the polar ring in NGC 660, juxtaposed against the exquisite crossing dust lanes, is simply beautiful. It really is the most incredible picture I've seen of the galaxy," Svoboda exclaims. "None of the other images I've seen, including those from the Hubble Space Telescope, show the star forming regions with such clarity." ### Weighing the Evidence If NGC represents a merging of two galaxies, astronomer would expect to find a collapsed core and a burst of star formation, which they do see. But the monkey wrench is the uniquely high gas content of both NGC 660’s disk component and its polar ring. "A tidal accretion event will place gas in the polar ring without strongly interacting with the original gas rich host," Svoboda explains. "Tidal interaction is consistent with an influx of gas into the nuclear region creating the starburst that we observe now." Further evidence, he says, is NGC 660's lack of a double nucleus (i.e. two super-massive black holes), which one would expect from a merger. Astronomers have not detected any "tails" extending from NGC 660, a key signature of many tidal interactions. Usually, when galaxy passes close to another, tidal forces eject stars, gas, and dust into a graceful tail of extragalactic debris and stretched them far into space. But both polar-ring models have produced systems without tidal tails while creating active star formation in the polar ring. While it can’t be proven with a great deal of confidence, in the case of NGC 660, Svoboda says, "I think that there is good evidence to suggest that the origin of the polar ring lies in the tidal accretion event scenario." Particularly he notes that the ring may be about 1 billion years old, so the stripped galaxy could have moved out of the field by the time of our observations now. ### Life from Death? Unseen to the eye, but bright at radio wavelengths, is a compact source (less than 32 light-years in extent) at the host’s core. Believed to be a super cluster of stars in a dense cloud of dust and gas, this powerful radio emitter contains perhaps a few thousand hot, blue youthful stars. Galaxies usually have a majority of old red stars at their cores, but one of the violent scenarios that created NGC 660 has triggered a furious burst of star formation at the galaxy’s core. Either way, the gravitational interaction between the two galaxies created shock waves that plowed into giant clouds of gas, causing them to collapse into behemoth blue stars, many likely containing more than 100 times the mass of our Sun. These monstrous, short-lived, stars exploded shortly thereafter as supernovae, which generated more shock waves, creating a domino effect that has ever since perpetuated the creation of youthful stars at NGC 660’s core. NGC 660, then, is not only a polar-ring galaxy but also a starburst galaxy. These systems are among the most dense and intense star-forming environments known. ### Probing Dark Matter The ring in a polar-ring galaxy rotates at a speed comparable to that of its host galaxy. By determining how fast a polar ring rotates at different distances from the center of the system, astronomers can search for evidence of elusive and mysterious dark matter in NGC 660’s halo. Radio observations have shown that while the ring’s velocity close to NGC 660’s core is normal, the velocity in the ring’s outer parts remains consistent; theoretically the rotational velocity should have dropped off significantly due to the region’s gas-poor environment. This finding points to the existence of huge amounts of dark matter in NGC 660. Astronomers believe dark matter influences the dynamics of all galaxies. Yet understanding dark matter remains one of the astronomy’s greatest challenges. Further observations of the enigmatic environment of NGC 660 may shed more light on this … well … dark matter. *Image: Gemini Observatory/AURA \[[high-resolution](http://www.gemini.edu/images/pio/press_release/2012/pr2012-9/ngc660_med_legacy.jpg)\]* *Caption: [Peter Michaud/Gemini Observatory](http://www.gemini.edu/node/11896)*
74oct-18-2012
Coils of Kepler --------------- In 1604, a new star appeared in the night sky that was much brighter than Jupiter and dimmed over several weeks. This event was witnessed by sky watchers including the famous astronomer Johannes Kepler. Centuries later, the debris from this exploded star is known as the Kepler supernova remnant. Astronomers have long studied the Kepler supernova remnant and tried to determine exactly what happened when the star exploded to create it. New analysis of a long observation from NASA's Chandra X-ray Observatory is providing more clues. This analysis suggests that the supernova explosion was not only more powerful, but might have also occurred at a greater distance, than previously thought. This image shows the Chandra data derived from more than 8 days worth of observing time. The X-rays are shown in five colors from lower to higher energies: red, yellow, green, blue, and purple. These various X-ray slices were then combined with an optical image from the Digitized Sky Survey (light yellow and blue), showing stars in the field. Previous analysis of this Chandra image has determined that the stellar explosion that created Kepler was what astronomers call a "Type Ia" supernova. This class of supernovas occurs when a white dwarf gains mass, either by pulling gas off a companion star or merging with another white dwarf, until it becomes unstable and is destroyed by a thermonuclear explosion. *Image: X-ray: NASA/CXC/SAO/D.Patnaude, Optical: DSS \[[high-resolution](http://chandra.harvard.edu/graphics/resources/desktops/2012/kepler_1680.jpg)\]* *Caption: [Megan Watzke/Chandra X-ray Observatory](http://chandra.harvard.edu/blog/node/396)*
75oct-17-2012
Valles Marineris in Infrared ---------------------------- This image covers a small portion of gigantic Coprates Chasma, part of Valles Marineris on Mars With enhanced IR colors, we see a portion of the very top of the south wall of the canyon, looking down onto the steep upper slopes. The colors indicate that diverse rock types are present. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2880/ESP_028962_1645.jpg)\]* *Caption: [Alfred McEwen](http://hirise.lpl.arizona.edu/ESP_028962_1645)*
76oct-16-2012
Anyone Else Think This Looks Like the Cookie Monster? ----------------------------------------------------- Ok, so maybe it's just me. But the superposition of younger craters on older craters (in this case two smaller craters upon the rim of an older crater) can result in landforms that appear to resemble more familiar shapes to human eyes. More generally, the Law of Superposition allows scientists to determine which surface features pre- and postdate others, leading to a better understanding of the geological history of different regions of Mercury's surface. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://www.nasa.gov/images/content/696351main_messenger_orbit_image20121012_1_full_full.jpg)\]* *Caption: [Mercury Messenger Team](http://www.nasa.gov/mission_pages/messenger/multimedia/messenger_orbit_image20121012_1.html)*
77oct-15-2012
Spinning Galaxy --------------- NGC 3344 is a glorious spiral galaxy around half the size of the Milky Way, which lies 25 million light-years distant. We are fortunate enough to see NGC 3344 face-on, allowing us to study its structure in detail. The galaxy features an outer ring swirling around an inner ring with a subtle bar structure in the centre. The central regions of the galaxy are predominately populated by young stars, with the galactic fringes also featuring areas of active star formation. Central bars are found in around two thirds of spiral galaxies. NGC 3344’s is clearly visible here, although it is not as dramatic as some (see for example heic1202). The high density of stars in galaxies’ central regions gives them enough gravitational influence to affect the movement of other stars in their galaxy. However, NGC 3344’s outer stars are moving in an unusual manner, although the presence of the bar cannot entirely account for this, leaving astronomers puzzled. It is possible that in its past NGC 3344 passed close by another galaxy and accreted stars from it, but more research is needed to state this with confidence. The image is a combination of exposures taken in visible and near-infrared light, using Hubble’s Advanced Camera for Surveys. The field of view is around 3.4 by 3.4 arcminutes, or around a tenth of the diameter of the full Moon. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1242a.jpg)\]* *Caption: [Space Telescope Science Institute](http://www.spacetelescope.org/images/potw1242a/)*
ESO78oct-14-2012
Carina Nebula Panorama ---------------------- This spectacular panoramic view combines a new image of the field around the Wolf–Rayet star WR 22 in the Carina Nebula (right) with an earlier picture of the region around the unique star Eta Carinae in the heart of the nebula (left). The picture was created from images taken with the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile. *Image: ESO. \[[high resolution](http://www.eso.org/public/images/eso1031b/)\] (This image is available as a mounted image in the [ESOshop](http://www.eso.org/public/shop/product/mountedimage_mounted_124/))*
79oct-13-2012
Star Formation in Berkeley 87 ----------------------------- Combined infrared and X-ray image of the region ON 2. This region is a site of active star formation, with new massive stars being born within the glowing clouds of gas and dust, as revealed by the Spitzer infrared telescope (red and green). New observations with the XMM-Newton telescope show that extended X-ray emission (blue) traces the stellar cradles. In a paper that was published in The Astrophysical Journal, this X-ray emission is explained by the interaction between accelerated particles and magnetic fields present in ON 2. *Image: L. M. Oskinova, R. A. Gruendl, Spitzer Space Telescope, JPL, NASA and ESA. \[[high-resolution](http://xmm.esac.esa.int/external/xmm_science/gallery/images/epicirac2.jpg)\]* *Caption: [ESA](http://xmm.esac.esa.int/external/xmm_science/gallery/public/level3.php?id=1063)*
80oct-12-2012
Mars Swirls ----------- Dark swirls made by Martian winds make intricate patterns on sand dunes in this Mars Reconnaissance Orbiter image. The HiRISE camera onboard the Mars Reconnaissance Orbiter is the most powerful of its kind ever sent to another planet. Its high resolution allows us to see Mars like never before, and helps other missions choose a safe spot to land for future exploration. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://solarsystem.nasa.gov/multimedia/gallery/Mars_Swirls.jpg)\]* *Caption: [NASA](http://solarsystem.nasa.gov/multimedia/display.cfm?Category=GreatShots&IM_ID=10203)*
Chandra X-ray Observatory Center81oct-11-2012
Planetary Nebulas ----------------- This gallery shows four planetary nebulas from the first systematic survey of such objects in the solar neighborhood made with NASA's Chandra X-ray Observatory. The planetary nebulas shown here are NGC 6543, also known as the Cat's Eye, NGC 7662, NGC 7009 and NGC 6826. In each case, X-ray emission from Chandra is colored purple and optical emission from the Hubble Space Telescope is colored red, green and blue. In the first part of this survey, published in a new paper, twenty one planetary nebulas within about 5000 light years of the Earth have been observed. The paper also includes studies of fourteen other planetary nebulas, within the same distance range, that Chandra had already observed. A planetary nebula represents a phase of stellar evolution that the Sun should experience several billion years from now. When a star like the Sun uses up all of the hydrogen in its core, it expands into a red giant, with a radius that increases by tens to hundreds of times. In this phase, a star sheds most of its outer layers, eventually leaving behind a hot core that will soon contract to form a dense white dwarf star. A fast wind emanating from the hot core rams into the ejected atmosphere, pushes it outward, and creates the graceful, shell-like filamentary structures seen with optical telescopes. The diffuse X-ray emission seen in about 30% of the planetary nebulas in the new Chandra survey, and all members of the gallery, is caused by shock waves as the fast wind collides with the ejected atmosphere. The new survey data reveal that the optical images of most planetary nebulas with diffuse X-ray emission display compact shells with sharp rims, surrounded by fainter halos. All of these compact shells have observed ages that are less than about 5000 years, which therefore likely represents the timescale for the strong shock waves to occur. About half of the planetary nebulas in the study show X-ray point sources in the center, and all but one of these point sources show high energy X-rays that may be caused by a companion star, suggesting that a high frequency of central stars responsible for ejecting planetary nebulas have companions. Future studies should help clarify the role of double stars in determining the structure and evolution of planetary nebulas. These results were published in the August 2012 issue of The Astronomical Journal. The first two authors are Joel Kastner and Rodolfo Montez Jr. of the Rochester Institute of Technology in New York, accompanied by 23 co-authors. NASA's Marshall Space Flight Center in Huntsville, Ala., manages the Chandra program for NASA's Science Mission Directorate in Washington. The Smithsonian Astrophysical Observatory controls Chandra's science and flight operations from Cambridge, Mass. *Image: X-ray: NASA/CXC/RIT/J.Kastner et al.; Optical: NASA/STScI \[[high-resolution](http://chandra.harvard.edu/photo/2012/pne/pne_lg.jpg)\]* *Caption: [Chandra space telescope](http://chandra.harvard.edu/photo/2012/pne/)*
82saturnhexagon.jpg
Saturn's Hexagon ---------------- A bizarre six-sided feature encircling the north pole of Saturn near 78 degrees north latitude has been spied by the visual and infrared mapping spectrometer on NASA's Cassini spacecraft. This image is one of the first clear images ever taken of the north polar region as seen from a unique polar perspective. Originally discovered and last observed by a spacecraft during NASA's Voyager flybys of the early 1980's, the new views of this polar hexagon taken in late 2006 prove that this is an unusually long-lived feature on Saturn. This image is the first to capture the entire feature and north polar region in one shot, and is also the first polar view using Saturn's thermal glow at 5 microns (seven times the wavelength visible to the human eye) as the light source. This allows the pole to be revealed during the nighttime conditions presently underway during north polar winter. Previous images from Voyager and from ground-based telescopes suffered from poor viewing perspectives, which placed the feature and the north pole at the extreme northern limb (edge) of the planet. To see the deep atmosphere at night, the infrared instrument images the thermal glow radiating from Saturn¿s depths. Clouds at depths about 75 kilometers (47 miles) lower than the clouds seen at visible wavelengths block this light, appearing dark in silhouette. To show clouds as features that are bright or white rather than dark, the original image has been contrast reversed to produce the image shown here. The nested set of alternating white and dark hexagons indicates that the hexagonal complex extends deep into the atmosphere, at least down to the 3-Earth-atmosphere pressure level, some 75 kilometers (47 miles) underneath the clouds seen by Voyager. Multiple images acquired over a 12-day period between Oct. 30 and Nov. 11, 2006, show that the feature is nearly stationary, and likely is an unusually strong pole-encircling planetary wave that extends deep into the atmosphere. This image was acquired from an average distance of 902,000 million kilometers (560,400 miles) above the cloud tops of Saturn. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://solarsystem.nasa.gov/multimedia/gallery/PIA09188_reduced.jpg)\]* *Caption: [NASA](http://solarsystem.nasa.gov/multimedia/display.cfm?Category=GreatShots&IM_ID=4803)*
ESO/B. Bailleul83oct-9-2012-2
Thor's Helmet ------------- This VLT image of the Thor’s Helmet Nebula was taken on the occasion of ESO’s 50th Anniversary, 5 October 2012, with the help of Brigitte Bailleul — winner of the Tweet Your Way to the VLT! competition. The observations were broadcast live over the internet from the Paranal Observatory in Chile. This object, also known as NGC 2359, lies in the constellation of Canis Major (The Great Dog). The helmet-shaped nebula is around 15 000 light-years away from Earth and is over 30 light-years across. The helmet is a cosmic bubble, blown as the wind from the bright, massive star near the bubble's centre sweeps through the surrounding molecular cloud. *Image: ESO/B. Bailleul \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1238a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso1238a/)*
84oct-8-2012
Dr. Seuss Crater ---------------- This complex crater was recently named to honor Theodor Seuss Geisel, better known as Dr. Seuss. Seuss crater is relatively fresh, its floor contains impact melt and hollows, and the impact has excavated materials with different color characteristics. These characteristics make the crater very interesting, slightly odd, and colorful in appearance, much like Seuss's illustrations. This image was acquired as a high-resolution targeted
85oct-7-2012
The Necklace Nebula ------------------- A giant cosmic necklace glows brightly in this NASA Hubble Space Telescope image. The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star. The nebula consists of a bright ring, measuring 12 trillion miles across, dotted with dense, bright knots of gas that resemble diamonds in a necklace. The knots glow brightly due to absorption of ultraviolet light from the central stars. A pair of stars orbiting very close together produced the nebula, also called PN G054.2-03.4. About 10,000 years ago one of the aging stars ballooned to the point where it enveloped its companion star. This caused the larger star to spin so fast that much of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star's equator, producing a dense ring. The embedded bright knots are the densest gas clumps in the ring. The stars are furiously whirling around each other, completing an orbit in a little more than a day. (For comparison, Mercury, the closest planet to the Sun, takes 88 days to orbit the Sun.) The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta (the Arrow). In this composite image, taken on July 2, 2011, Hubble's Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red). *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/nebula/2011/24/image/a/)\]* *Caption: NASA, ESA, and the Hubble Heritage Team (STScI/AURA)*
86oct-6-2012
Cubesat Release --------------- Several tiny satellites are featured in this image photographed by an Expedition 33 crew member on the International Space Station. The satellites were released outside the Kibo laboratory using a Small Satellite Orbital Deployer attached to the Japanese module's robotic arm on Oct. 4, 2012. Japan Aerospace Exploration Agency astronaut Aki Hoshide, flight engineer, set up the satellite deployment gear inside the lab and placed it in the Kibo airlock. The Japanese robotic arm then grappled the deployment system and its satellites from the airlock for deployment. A portion of the station's solar array panels and a blue and white part of Earth provide the backdrop for the scene. *Image: NASA \[[high-resolution](http://spaceflight.nasa.gov/gallery/images/station/crew-33/hires/iss033e009285.jpg)\]* *Caption: [NASA](http://spaceflight.nasa.gov/gallery/images/station/crew-33/html/iss033e009285.html)*
87oct-5-2012
Dying Star's Temper Tantrum --------------------------- A dying star is throwing a cosmic tantrum in this combined image from NASA's Spitzer Space Telescope and the Galaxy Evolution Explorer (GALEX), which NASA has lent to the California Institute of Technology in Pasadena. In death, the star's dusty outer layers are unraveling into space, glowing from the intense ultraviolet radiation being pumped out by the hot stellar core. This object, called the Helix nebula, lies 650 light-years away, in the constellation of Aquarius. Also known by the catalog number NGC 7293, it is a typical example of a class of objects called planetary nebulae. Discovered in the 18th century, these cosmic works of art were erroneously named for their resemblance to gas-giant planets. Planetary nebulae are actually the remains of stars that once looked a lot like our sun. These stars spend most of their lives turning hydrogen into helium in massive runaway nuclear fusion reactions in their cores. In fact, this process of fusion provides all the light and heat that we get from our sun. Our sun will blossom into a planetary nebula when it dies in about five billion years. When the hydrogen fuel for the fusion reaction runs out, the star turns to helium for a fuel source, burning it into an even heavier mix of carbon, nitrogen and oxygen. Eventually, the helium will also be exhausted, and the star dies, puffing off its outer gaseous layers and leaving behind the tiny, hot, dense core, called a white dwarf. The white dwarf is about the size of Earth, but has a mass very close to that of the original star; in fact, a teaspoon of a white dwarf would weigh as much as a few elephants! The glow from planetary nebulae is particularly intriguing as it appears surprisingly similar across a broad swath of the spectrum, from ultraviolet to infrared. The Helix remains recognizable at any of these wavelengths, but the combination shown here highlights some subtle differences. The intense ultraviolet radiation from the white dwarf heats up the expelled layers of gas, which shine brightly in the infrared. GALEX has picked out the ultraviolet light pouring out of this system, shown throughout the nebula in blue, while Spitzer has snagged the detailed infrared signature of the dust and gas in yellow A portion of the extended field beyond the nebula, which was not observed by Spitzer, is from NASA's all-sky Wide-field Infrared Survey Explorer (WISE). The white dwarf star itself is a tiny white pinprick right at the center of the nebula. The brighter purple circle in the very center is the combined ultraviolet and infrared glow of a dusty disk circling the white dwarf (the disk itself is too small to be resolved). This dust was most likely kicked up by comets that survived the death of their star. Before the star died, its comets, and possibly planets, would have orbited the star in an orderly fashion. When the star ran out of hydrogen to burn, and blew off its outer layers, the icy bodies and outer planets would have been tossed about and into each other, kicking up an ongoing cosmic dust storm. Any inner planets in the system would have burned up or been swallowed as their dying star expanded. Infrared data from Spitzer for the central nebula is rendered in green (wavelengths of 3.6 to 4.5 microns) and red (8 to 24 microns), with WISE data covering the outer areas in green (3.4 to 4.5 microns) and red (12 to 22 microns). Ultraviolet data from GALEX appears as blue (0.15 to 2.3 microns). *Image: NASA/JPL-Caltech \[[high-resolution](http://www.nasa.gov/images/content/693952main_pia15817-full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2368.html)*
88oct-4-2012
Colorful Crater Wall -------------------- This image covers most of an impact crater on Mars about 6 to 7 kilometers wide. Partway down from the crater rim is a prominent bright layer of bedrock. The full-resolution color data shows three distinct bedrock colors: yellow, light blue-green, and dark blue (in enhanced infrared colors). (North is down in the cutout, so the crater rim is near the top, which helps my brain to interpret the geometry.) These layers must correspond to different types of rock that were deposited as nearly flat-lying sheets, perhaps a combination of lava flows and sediments. The relatively blue colors in HiRISE infrared color often correspond to minerals like olivine and pyroxene that are common in lava. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://www.uahirise.org/images/wallpaper/2880/ESP_028693_1535.jpg)\]* *Caption: [Alfred McEwen](http://www.uahirise.org/ESP_028693_1535)*
89oct-3-2012
Pluto and Moons --------------- This image, taken by NASA's Hubble Space Telescope, shows five moons orbiting the distant, icy dwarf planet Pluto. The green circle marks the newly discovered moon, designated P5, as photographed by Hubble's Wide Field Camera 3 on July 7. Other observations that collectively show the moon's orbital motion were taken on June 26, 27, 29, and July 9, 2012. The moon is estimated to be 6 to 15 miles across. It is in a 58,000-mile-diameter circular orbit around Pluto that is assumed to be co-planar with the other satellites in the system. The observations will help scientists in their planning for the July 2015 flyby of Pluto by NASA's New Horizons spacecraft. *Image: NASA, ESA, and M. Showalter (SETI Institute) \[[high-resolution](http://www.nasa.gov/images/content/666710main_p1232ay.jpg)\]* *Caption: [Hubble Site](http://hubblesite.org/newscenter/archive/releases/2012/32/image/a/)*
90oct-2-2012
Jupiter's Rings Revealed ------------------------ Why does Jupiter have rings? Jupiter's rings were discovered in 1979 by the passing Voyager 1 spacecraft, but their origin was a mystery. Data from the Galileo spacecraft that orbited Jupiter from 1995 to 2003 later confirmed that these rings were created by meteoroid impacts on small nearby moons. As a small meteoroid strikes tiny Adrastea, for example, it will bore into the moon, vaporize and explode dirt and dust off into a Jovian orbit. Pictured above is an eclipse of the sun by Jupiter, as viewed from Galileo. Small dust particles high in Jupiter's atmosphere, as well as the dust particles that compose the rings, can be seen by reflected sunlight. *Image: NASA \[[high-resolution](http://solarsystem.nasa.gov/multimedia/gallery/208152main_jupring1_gal_big_full.jpg)\]* *Caption: [NASA](http://solarsystem.nasa.gov/multimedia/display.cfm?Category=GreatShots&IM_ID=12584)*
NASA/JPL-Caltech/L. Rebull (SSC/91oct-1-2012
Four Views of North America Nebula ---------------------------------- This image layout reveals how the appearance of the North America nebula can change dramatically using different combinations of visible and infrared observations from the Digitized Sky Survey and NASA's Spitzer Space Telescope, respectively. In this progression, the visible-light view (upper left) shows a striking similarity to the North America continent. The image highlights the eastern seaboard and Gulf of Mexico regions. The red region to the right is known as the "Pelican nebula," after its resemblance in visible light to a pelican. The view at upper right includes both visible and infrared observations. The hot gas comprising the North America continent and the Pelican now takes on a vivid blue hue, while red colors display the infrared light. Inky black dust features start to glow in the infrared view. In the bottom two images, only infrared light from Spitzer is shown -- data from the infrared array camera is on the left, and data from both the infrared array camera and the multiband imaging photometer, which sees longer wavelengths, is on the right. These pictures look different in part because infrared light can penetrate dust whereas visible light cannot. Dusty, dark clouds in the visible image become transparent in Spitzer's view. In addition, Spitzer's infrared detectors pick up the glow of dusty cocoons enveloping baby stars. Color is used to display different parts of the spectrum in each of these images. In the visible-light view (upper right) from the Digitized Sky Survey, colors are shown in their natural blue and red hues. The combined visible/infrared image (upper left) shows visible light as blue, and infrared light as green and red. The infrared array camera (lower left) represents light with a wavelength of 3.6 microns as blue, 4.5 microns as green, 5.8 microns as orange, and 8.0 microns as red. In the final image, incorporating the multiband imaging photometer data, light with a wavelength of 3.6 microns has been color coded blue; 4.5-micron light is blue-green; 5.8-micron and 8.0-micron light are green; and 24-micron light is red. *Image: NASA/JPL-Caltech/L. Rebull (SSC/Caltech) \[[high-resolution](http://www.spitzer.caltech.edu/uploaded_files/images/0007/8740/ssc2011-03a_Med.jpg)\]* *Caption: [Spitzer Space Telescope](http://www.spitzer.caltech.edu/images/3508-ssc2011-03a-Changing-Face-of-the-North-America-Nebula)*
92sept-28-2012
Evil Eye Galaxy --------------- A collision of two galaxies has left a merged star system with an unusual appearance as well as bizarre internal motions. Messier 64 (M64) has a spectacular dark band of absorbing dust in front of the galaxy's bright nucleus, giving rise to its nicknames of the "Black Eye" or "Evil Eye" galaxy. Fine details of the dark band are revealed in this image of the central portion of M64 obtained with the Hubble Space Telescope. M64 is well known among amateur astronomers because of its appearance in small telescopes. It was first cataloged in the 18th century by the French astronomer Messier. Located in the northern constellation Coma Berenices, M64 resides roughly 17 million light-years from Earth. At first glance, M64 appears to be a fairly normal pinwheel-shaped spiral galaxy. As in the majority of galaxies, all of the stars in M64 are rotating in the same direction, clockwise as seen in the Hubble image. However, detailed studies in the 1990's led to the remarkable discovery that the interstellar gas in the outer regions of M64 rotates in the opposite direction from the gas and stars in the inner regions. Active formation of new stars is occurring in the shear region where the oppositely rotating gases collide, are compressed, and contract. Particularly noticeable in the image are hot, blue young stars that have just formed, along with pink clouds of glowing hydrogen gas that fluoresce when exposed to ultraviolet light from newly formed stars. Astronomers believe that the oppositely rotating gas arose when M64 absorbed a satellite galaxy that collided with it, perhaps more than one billion years ago. This small galaxy has now been almost completely destroyed, but signs of the collision persist in the backward motion of gas at the outer edge of M64. This image of M64 was taken with Hubble's Wide Field Planetary Camera 2 (WFPC2). The color image is a composite prepared by the Hubble Heritage Team from pictures taken through four different color filters. These filters isolate blue and near-infrared light, along with red light emitted by hydrogen atoms and green light from Strömgren y. *Image: NASA and The Hubble Heritage Team (AURA/STScI) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2004-04-a-full_jpg.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2004/04/image/a/)*
93sept-27-2012
The Cosmic Seagull ------------------ This new image from ESO’s La Silla Observatory shows part of a stellar nursery nicknamed the Seagull Nebula. This cloud of gas, formally called Sharpless 2-292, seems to form the head of the seagull and glows brightly due to the energetic radiation from a very hot young star lurking at its heart. The detailed view was produced by the Wide Field Imager on the MPG/ESO 2.2-metre telescope. Nebulae are among the most visually impressive objects in the night sky. They are interstellar clouds of dust, molecules, hydrogen, helium and other ionised gases where new stars are being born. Although they come in different shapes and colours many share a common characteristic: when observed for the first time, their odd and evocative shapes trigger astronomers’ imaginations and lead to curious names. This dramatic region of star formation, which has acquired the nickname of the Seagull Nebula, is no exception. This new image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile shows the head part of the Seagull Nebula. It is just one part of the larger nebula known more formally as IC 2177, which spreads its wings with a span of over 100 light-years and resembles a seagull in flight. This cloud of gas and dust is located about 3700 light-years away from Earth. The entire bird shows up best in wide-field images. The Seagull Nebula lies just on the border between the constellations of Monoceros (The Unicorn) and Canis Major (The Great Dog) and is close to Sirius, the brightest star in the night sky. The nebula lies more than four hundred times further away than the famous star. The complex of gas and dust that forms the head of the seagull glows brightly in the sky due to the strong ultraviolet radiation coming mostly from one brilliant young star — HD 53367 — that can be spotted in the centre of the image and could be taken to be the seagull’s eye. The radiation from the young stars causes the surrounding hydrogen gas to glow with a rich red colour and become an HII region \[3\]. Light from the hot blue-white stars is also scattered off the tiny dust particles in the nebula to create a contrasting blue haze in some parts of the picture. Although a small bright clump in the Seagull Nebula complex was observed for the first time by the German-British astronomer Sir William Herschel back in 1785, the part shown here had to await photographic discovery about a century later. By chance this nebula lies close in the sky to the Thor’s Helmet Nebula (NGC 2359), which was the winner of ESO’s recent Choose what the VLT Observes contest (ann12060). This nebula, with its distinctive shape and unusual name, was picked as the first ever object selected by members of the public to be observed by ESO’s Very Large Telescope. These observations are going to be part of the celebrations on the day of ESO’s 50th anniversary, 5 October 2012. The observations will be streamed live from the VLT on Paranal. Stay tuned! *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1237a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/news/eso1237/)*
94sept-26-2012
Saturn From Below ----------------- The Cassini spacecraft takes an angled view toward Saturn, showing the southern reaches of the planet with the rings on a dramatic diagonal. North on Saturn is up and rotated 16 degrees to the left. This view looks toward the southern, unilluminated side of the rings from about 14 degrees below the ringplane. The rings cast wide shadows on the planet's southern hemisphere. The moon Enceladus (313 miles, or 504 kilometers across) appears as a small, bright speck in the lower left of the image. The image was taken with the Cassini spacecraft wide-angle camera on June 15, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 752 nanometers. The view was obtained at a distance of approximately 1.8 million miles (2.9 million kilometers) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 72 degrees. Image scale is 11 miles (17 kilometers) per pixel. *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://www.nasa.gov/images/content/690985main_pia14627-full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/cassini/multimedia/pia14627.html)*
NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team95sept-25-2012
Hubble Goes Extremely Deep -------------------------- Like photographers assembling a portfolio of their best shots, astronomers have assembled a new, improved portrait of our deepest-ever view of the Universe. Called the eXtreme Deep Field, or XDF, the photo was assembled by combining ten years of NASA/ESA Hubble Space Telescope observations taken of a patch of sky within the original Hubble Ultra Deep Field. The XDF is a small fraction of the angular diameter of the full Moon. The Hubble Ultra Deep Field is an image of a small area of space in the constellation of Fornax (The Furnace), created using Hubble Space Telescope data from 2003 and 2004. By collecting faint light over one million seconds of observation, the resulting image revealed thousands of galaxies, both nearby and very distant, making it the deepest image of the Universe ever taken at that time. The new full-colour XDF image is even more sensitive than the original Hubble Ultra Deep Field image, thanks to the additional observations, and contains about 5500 galaxies, even within its smaller field of view. The faintest galaxies are one ten-billionth the brightness that the unaided human eye can see. Magnificent spiral galaxies similar in shape to the Milky Way and its neighbour the Andromeda galaxy appear in this image, as do large, fuzzy red galaxies in which the formation of new stars has ceased. These red galaxies are the remnants of dramatic collisions between galaxies and are in their declining years as the stars within them age. Peppered across the field are tiny, faint, and yet more distant galaxies that are like the seedlings from which today’s magnificent galaxies grew. The history of galaxies — from soon after the first galaxies were born to the great galaxies of today, like the Milky Way — is laid out in this one remarkable image. Hubble pointed at a tiny patch of southern sky in repeat visits made over the past decade with a total exposure time of two million seconds.More than 2000 images of the same field were taken with Hubble’s two primary cameras: the Advanced Camera for Surveys and the Wide Field Camera 3, which extends Hubble’s vision into near-infrared light. These were then combined to form the XDF. “The XDF is the deepest image of the sky ever obtained and reveals the faintest and most distant galaxies ever seen. XDF allows us to explore further back in time than ever before,” said Garth Illingworth of the University of California at Santa Cruz, principal investigator of the Hubble Ultra Deep Field 2009 (HUDF09) programme. The Universe is 13.7 billion years old, and the XDF reveals galaxies that span back 13.2 billion years in time. Most of the galaxies in the XDF are seen when they were young, small, and growing, often violently as they collided and merged together. The early Universe was a time of dramatic birth for galaxies containing brilliant blue stars far brighter than our Sun. The light from those past events is just arriving at Earth now, and so the XDF is a time tunnel into the distant past when the Universe was just a fraction of its current age. The youngest galaxy found in the XDF existed just 450 million years after the Universe’s birth in the Big Bang. Before Hubble was launched in 1990, astronomers were able to see galaxies up to about seven billion light-years away, half way back to the Big Bang. Observations with telescopes on the ground were not able to establish how galaxies formed and evolved in the early Universe. Hubble gave astronomers their first view of the actual forms of galaxies when they were young. This provided compelling, direct visual evidence that the Universe is truly changing as it ages. Like watching individual frames of a motion picture, the Hubble deep surveys reveal the emergence of structure in the infant Universe and the subsequent dynamic stages of galaxy evolution. The planned NASA/ESA/CSA James Webb Space Telescope (Webb telescope) will be aimed at the XDF, and will study it with its infrared vision. The Webb telescope will find even fainter galaxies that existed when the Universe was just a few hundred million years old. Because of the expansion of the Universe, light from the distant past is stretched into longer, infrared wavelengths. The Webb telescope’s infrared vision is ideally suited to push the XDF even deeper, into a time when the first stars and galaxies formed and filled the early “dark ages” of the Universe with light. *Image: NASA, ESA, G. Illingworth, D. Magee, and P. Oesch (University of California, Santa Cruz), R. Bouwens (Leiden University), and the HUDF09 Team \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/heic1214a.jpg)\]* *Caption: [Hubble Heritage Team](http://www.spacetelescope.org/news/heic1214/)*
96sept-24-2012
Clay Color Inspiration ---------------------- This image (taken by the [HiRISE camera](http://hirise.lpl.arizona.edu/) on NASA's Mars Reconnaissance Orbiter) covers a exposure of clay-rich bedrock on the "shore" of the Northern plains, north of Mawrth Vallis on Mars. The relatively bright areas reveal a complex terrain with a range of textures and enhanced colors. We probably need to send a rover here to understand the complex history of these very ancient deposits. *Image: NASA/JPL/University of Arizona. \[[high-resolution](http://hirise.lpl.arizona.edu/images/2012/details/cut/ESP_028367_2085.jpg)\]* *Caption: Alfred McEwen*
97sept-21-2012
Lunar Landslide --------------- When the La Pérouse A impact excavated material from the side of a hill of highland material (1.5 to 2 km taller than the plains to the west), the slope became unstable and collapsed into the crater La Pérouse A on the moon. The result is a crater with one rim 920 meters higher than the other. The Featured Image shows the top of this landslide, now the new rim of La Pérouse A. The landslide material inside the rim is high reflectance, while the undisturbed section of the highland material is relatively darker. Despite being the same composition, the landslide material is higher reflectance since it is fresh (recently uncovered). Faint lines along the outer edge of the rim are evidence of highland material slumping towards the crater. Collapse features on the Moon often display slump lines, which show where material has fractured and moved downwards, but not completely collapsed. Subsequent impacts or seismic shaking could cause further landslides inside the crater! *Image: NASA/GSFC/Arizona State University \[[high-resolution](http://lroc.sese.asu.edu/news/uploads/LROCiotw/M152390311RE_thumb1.png)\]* *Caption: [Sarah Braden/Lunar Reconnaissance Orbiter Camera](http://lroc.sese.asu.edu/news/index.php?/archives/633-Top-of-the-Landslide.html)*
98sept-20-2012
Stellar Sibling Rivalry ----------------------- This NASA Hubble Space Telescope image of the Trifid Nebula reveals a stellar nursery being torn apart by radiation from a nearby, massive star. The picture also provides a peek at embryonic stars forming within an ill-fated cloud of dust and gas, which is destined to be eaten away by the glare from the massive neighbor. This stellar activity is a beautiful example of how the life cycles of stars like our Sun is intimately connected with their more powerful siblings. The Hubble image shows a small part of a dense cloud of dust and gas, a stellar nursery full of embryonic stars. This cloud is about 8 light-years away from the nebula's central star, which is beyond the top of this picture. Located about 9,000 light-years from Earth, the Trifid resides in the constellation Sagittarius. A stellar jet \[the thin, wispy object pointing to the upper left\] protrudes from the head of a dense cloud and extends three-quarters of a light-year into the nebula. The jet's source is a very young stellar object that lies buried within the cloud. Jets such as this are the exhaust gases of star formation. Radiation from the massive star at the center of the nebula is making the gas in the jet glow, just as it causes the rest of the nebula to glow. The jet in the Trifid is a "ticker tape," telling the history of one particular young stellar object that is continuing to grow as its gravity draws in gas from its surroundings. But this particular ticker tape will not run for much longer. Within the next 10,000 years the glare from the central, massive star will continue to erode the nebula, overrunning the forming star, and bringing its growth to an abrupt and possibly premature end. Another nearby star may have already faced this fate. The Hubble picture shows a "stalk" \[the finger-like object\] pointing from the head of the dense cloud directly toward the star that powers the Trifid. This stalk is a prominent example of the evaporating gaseous globules, or "EGGs," that were seen previously in the Eagle Nebula, another star-forming region photographed by Hubble. The stalk has survived because at its tip there is a knot of gas that is dense enough to resist being eaten away by the powerful radiation. Reflected starlight at the tip of the EGG may be due to light from the Trifid's central star, or from a young stellar object buried within the EGG. Similarly, a tiny spike of emission pointing outward from the EGG looks like a small stellar jet. Hubble astronomers are tentatively interpreting this jet as the last gasp from a star that was cut off from its supply lines 100,000 years ago. The images were taken Sept. 8, 1997 through filters that isolate emission from hydrogen atoms, ionized sulfur atoms, and doubly ionized oxygen atoms. The images were combined in a single color composite picture. While the resulting picture is not true color, it is suggestive of what a human eye might see. *Image: NASA and Jeff Hester (Arizona State University) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-1999-42-a-full_jpg.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/1999/42/image/a/)*
99sept-19-2012
Titan Vortex ------------ The vortex, which is a mass of gas swirling around the south pole high in the moon's atmosphere, can be seen in the lower right of this view. The moon's northern hood is also visible in the top left of this view. This view looks toward the leading hemisphere of Titan (3,200 miles, or 5,150 kilometers across). North on Titan is up and rotated 25 degrees to the left. The image was taken with the Cassini spacecraft narrow-angle camera on July 6, 2012 using a spectral filter sensitive to wavelengths of near-infrared light centered at 889 nanometers. The view was acquired at a distance of approximately 1.7 million miles (2.8 million kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 86 degrees. Scale in the original image was 11 miles (17 kilometers) per pixel. The image was contrast enhanced and magnified by a factor of 1.5 to enhance the visibility of surface features. *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA14626.jpg)\]* *Caption: [Cassini Solstice Team](http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4640)*
ESO100sept-18-2012
Horsehead Nebula ---------------- A reproduction of a composite colour image of the Horsehead Nebula and its immediate surroundings. It is based on three exposures in the visual part of the spectrum with the FORS2 multi-mode instrument at the 8.2-m KUEYEN telescope at Paranal. It was produced from three images, obtained on February 1, 2000, with the FORS2 multi-mode instrument at the 8.2-m KUEYEN Unit Telescope and extracted from the VLT Science Archive Facility . The frames were obtained in the B-band (600 sec exposure; wavelength 429 nm; FWHM 88 nm; here rendered as blue), V-band (300 sec; 554 nm; 112 nm; green) and R-band (120 sec; 655 nm; 165 nm; red). The original pixel size is 0.2 arcsec. The photo shows the full field recorded in all three colours, approximately 6.5 x 6.7 arcmin 2 . The seeing was about 0.75 arcsec. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso0202a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0202a/)*
101sept-17-2012
Gravitational Lens ------------------ This image from the NASA/ESA Hubble Space Telescope shows the galaxy cluster MACS J1206. Galaxy clusters like these have enormous mass, and their gravity is powerful enough to visibly bend the path of light, somewhat like a magnifying glass. These so-called lensing clusters are useful tools for studying very distant objects, because this lens-like behaviour amplifies the light from faraway galaxies in the background. They also contribute to a range of topics in cosmology, as the precise nature of the lensed images encapsulates information about the properties of spacetime and the expansion of the cosmos. This is one of 25 clusters being studied as part of the CLASH (Cluster Lensing and Supernova survey with Hubble) programme, a major project to build a library of scientific data on lensing clusters. *Image: NASA, ESA, M. Postman (STScI) and the CLASH Team \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/heic1115a.jpg)\]* *Caption: [Hubble Heritage Team](http://www.spacetelescope.org/images/heic1115a/)*
102sept-14-2012
Mickey on Mercury ----------------- This scene is to the northwest of the recently named crater Magritte, in Mercury's south. The image is not map projected; the larger crater actually sits to the north of the two smaller ones. The shadowing helps define the striking "Mickey Mouse" resemblance, created by the accumulation of craters over Mercury's long geologic history. This image was acquired as part of MDIS's high-incidence-angle base map. The high-incidence-angle base map is a major mapping activity in MESSENGER's extended mission and complements the surface morphology base map of MESSENGER's primary mission that was acquired under generally more moderate incidence angles. High incidence angles, achieved when the Sun is near the horizon, result in long shadows that accentuate the small-scale topography of geologic features. The high-incidence-angle base map is being acquired with an average resolution of 200 meters/pixel. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA15862.jpg)\]* *Caption: [Mercury Messenger Team](http://photojournal.jpl.nasa.gov/catalog/PIA15862)*
Spitzer Space Telescope103sept-13-2012
Composite Crab Nebula --------------------- A star's spectacular death in the constellation Taurus was observed on Earth as the supernova of 1054 A.D. Now, almost a thousand years later, a super dense object -- called a neutron star -- left behind by the explosion is seen spewing out a blizzard of high-energy particles into the expanding debris field known as the Crab Nebula. X-ray data from Chandra provide significant clues to the workings of this mighty cosmic "generator," which is producing energy at the rate of 100,000 suns. his composite image uses data from three of NASA's Great Observatories. The Chandra X-ray image is shown in blue, the Hubble Space Telescope optical image is in red and yellow, and the Spitzer Space Telescope's infrared image is in purple. The X-ray image is smaller than the others because extremely energetic electrons emitting X-rays radiate away their energy more quickly than the lower-energy electrons emitting optical and infrared light. Along with many other telescopes, Chandra has repeatedly observed the Crab Nebula over the course of the mission's lifetime. The Crab Nebula is one of the most studied objects in the sky, truly making it a cosmic icon. *Image: X-Ray: NASA/CXC/J.Hester (ASU); Optical: NASA/ESA/J.Hester & A.Loll (ASU); Infrared: NASA/JPL-Caltech/R.Gehrz (Univ. Minn) \[[high-resolution](http://www.spitzer.caltech.edu/uploaded_files/images/0007/9500/sig09-009.jpg)\]* *Caption: [Spitzer Space Telescope](http://www.spitzer.caltech.edu/images/2857-sig09-009-NASA-s-Great-Observatories-View-of-the-Crab-Nebula)*
104sept-12-2012
Witch's Broom ------------- The Pencil Nebula is pictured in a new image from ESO’s La Silla Observatory in Chile. This peculiar cloud of glowing gas is part of a huge ring of wreckage left over after a supernova explosion that took place about 11 000 years ago. This detailed view was produced by the Wide Field Imager on the MPG/ESO 2.2-metre telescope. Despite the tranquil and apparently unchanging beauty of a starry night, the Universe is far from being a quiet place. Stars are being born and dying in an endless cycle, and sometimes the death of a star can create a vista of unequalled beauty as material is blasted out into space to form strange structures in the sky. This new image from the Wide Field Imager on the MPG/ESO 2.2-metre telescope at ESO’s La Silla Observatory in Chile shows the Pencil Nebula against a rich starry background. This oddly shaped cloud, which is also known as NGC 2736, is a small part of a supernova remnant in the southern constellation of Vela (The Sails). These glowing filaments were created by the violent death of a star that took place about 11 000 years ago. The brightest part resembles a pencil; hence the name, but the whole structure looks rather more like a traditional witch’s broom. The Vela supernova remnant is an expanding shell of gas that originated from the supernova explosion. Initially the shock wave was moving at millions of kilometres per hour, but as it expanded through space it ploughed through the gas between the stars, which has slowed it considerably and created strangely shaped folds of nebulosity. The Pencil Nebula is the brightest part of this huge shell. This new image shows large, wispy filamentary structures, smaller bright knots of gas and patches of diffuse gas. The nebula's luminous appearance comes from dense gas regions that have been struck by the supernova shock wave. As the shock wave travels through space, it rams into the interstellar material. At first, the gas was heated to millions of degrees, but it then subsequently cooled down and is still giving off the faint glow that was captured in the new image. By looking at the different colours of the nebula, astronomers have been able to map the temperature of the gas. Some regions are still so hot that the emission is dominated by ionised oxygen atoms, which glow blue in the picture. Other cooler regions are seen glowing red, due to emission from hydrogen. The Pencil Nebula measures about 0.75 light-years across and is moving through the interstellar medium at about 650 000 kilometres per hour. Remarkably, even at its distance of approximately 800 light-years from Earth, this means that it will noticeably change its position relative to the background stars within a human lifetime. Even after 11 000 years the supernova explosion is still changing the face of the night sky. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1236a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/news/eso1236/)*
105sept-11-2012
Goodbye Vesta ------------- As NASA's Dawn spacecraft takes off for its next destination, this mosaic synthesizes some of the best views the spacecraft had of the giant asteroid Vesta. Dawn studied Vesta from July 2011 to September 2012. The towering mountain at the south pole — more than twice the height of Mount Everest — is visible at the bottom of the image. The set of three craters known as the "snowman" can be seen at the top left. These images are the last in Dawn's Image of the Day series during the cruise to Dawn's second destination, Ceres. A full set of Dawn data is being archived at http://pds.nasa.gov/ . *Image: NASA/JPL-Caltech/UCAL/MPS/DLR/IDA \[[high-resolution](http://www.nasa.gov/images/content/685735main_pia15678-43_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/dawn/multimedia/pia15678.html)*
106sept-10-2012
Galaxy in Pink -------------- This image portrays a beautiful view of the galaxy NGC 7090, as seen by the NASA/ESA Hubble Space Telescope. The galaxy is viewed edge-on from the Earth, meaning we cannot easily see the spiral arms, which are full of young, hot stars. However, our side-on view shows the galaxy’s disc and the bulging central core, where typically a large group of cool old stars are packed in a compact, spheroidal region. In addition, there are two interesting features present in the image that are worth mentioning. First, we are able to distinguish an intricate pattern of pinkish red regions over the whole galaxy. This indicates the presence of clouds of hydrogen gas. These structures trace the location of ongoing star formation, visual confirmation of recent studies that classify NGC 7090 as an actively star-forming galaxy. Second, we observe dust lanes, depicted as dark regions inside the disc of the galaxy. In NGC 7090, these regions are mostly located in lower half of the galaxy, showing an intricate filamentary structure. Looking from the outside in through the whole disc, the light emitted from the bright centre of the galaxy is absorbed by the dust, silhouetting the dusty regions against the bright light in the background. Dust in our galaxy, the Milky Way, has been one of the worst enemies of observational astronomers for decades. But this does not mean that these regions are quite blind spots in the sky. At near-infrared wavelengths — slightly longer wavelengths than visible light — this dust is largely transparent and astronomers are able to study what is really behind it. At still longer wavelengths, the realm of radio astronomy, the dust itself can actually be observed, letting astronomers study the structure and properties of dust clouds and their relationship with star formation. Lying in the southern constellation of Indus (The Indian), NGC 7090 is located about thirty million light-years from the Sun. Astronomer John Herschel first observed this galaxy on 4 October, 1834. The image was taken using the Wide Field Channel of the Advanced Camera for Surveys aboard the Hubble Space Telescope and combines orange light (coloured blue here), infrared (coloured red) and emissions from glowing hydrogen gas (also in red). A version of this image of NGC 7090 was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant Rasid Tugral. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. *Image: ESA/Hubble & NASA Acknowledgement: R. Tugral \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1237a.jpg)\]* *Caption: [Hubble Heritage Team](http://www.spacetelescope.org/images/potw1237a/)*
107sept-7-2012
Weird Streaks ------------- This observation shows a portion of the wall (light-toned material) and floor of a trough in the Acheron Fossae region of Mars. Many dark and light-toned slope streaks are visible on the wall of the trough surrounded by dunes. Slope streak formation is among the few known processes currently active on Mars. While the mechanism of formation and triggering is debated, they are most commonly believed to form by downslope movement of extremely dry sand or very fine-grained dust in an almost fluidlike manner (analogous to a terrestrial snow avalanche) exposing darker underlying material. Some of the slope streaks show evidence that downslope movement is being diverted around obstacles, such as large boulders, and a few appear to originate at boulders or clumps of rocky material. These slope streaks, as well as others on the planet, do not have deposits of displaced material at their downslope ends. The darkest slope streaks are youngest and can be seen to cross cut and lie on top of the older and lighter-toned streaks. The lighter-toned streaks are believed to be dark streaks that are lightening with time as new dust is deposited on their surface. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://www.uahirise.org/images/wallpaper/2560/PSP_001656_2175.jpg)\]* *Caption: [Maria Banks](http://www.uahirise.org/PSP_001656_2175)*
108sept-6-2012
Neighboring Galaxies -------------------- Two very different galaxies feature in this family portrait taken by the NASA/ESA Hubble Space Telescope, together forming a peculiar galaxy pair called Arp 116. The image shows the dramatic differences in size, structure and colour between spiral and elliptical galaxies. Arp 116 is composed of a giant elliptical galaxy known as Messier 60, and a much smaller spiral galaxy, NGC 4647. Being a typical elliptical galaxy, Messier 60 on its own may not be very exciting to look at, but together with its adjacent spiral friend, the pair becomes a rather interesting feature in the night sky. Messier 60 is very bright — the third brightest in the Virgo cluster of galaxies, a collection of more than 1300 galaxies. It is noticeably larger than its neighbour, and has a far higher mass of stars. M 60, like other elliptical galaxies, has a golden colour because of the many old, cool and red stars in it. NGC 4647, on the other had, has many young and hot stars that glow blue, giving the galaxy a noticeably different hue. Astronomers have long tried to determine whether these two galaxies are actually interacting. Although they overlap as seen from Earth, there is no clear evidence of vigorous new star formation. In interacting pairs of galaxies, the mutual gravitational pull that the galaxies exert on each other typically disrupts gas clouds, much like tides on Earth are caused by the Moon’s gravity. This disruption can cause gas clouds to collapse, forming a sudden burst of new stars. Although this does not appear to have happened in Arp 116, studies of very detailed Hubble images suggest the onset of some tidal interaction between the two. Regardless of whether they are actually close enough to be interacting, however, the two galaxies are certainly near neighbours. This means we see the two galaxies at the same scale, making Hubble’s family portrait a textbook example of how giant elliptical galaxies differ in size, structure and colour from their smaller spiral brethren. Surprisingly Messier 60 was discovered independently by three different astronomers in 1779. Johann Gottfried Koehler of Dresden first spotted it on 11 April that year while observing a comet, the Italian Barnabus Oriani noticed it a day later, and the French Charles Messier saw it on 15 April. Charles Messier then listed the galaxy in the Messier Catalogue. Having photographed the galaxy pair with the 5-metre Hale telescope, US astronomer Halton Arp included it in his Atlas of Peculiar Galaxies, published in 1966. The catalogue contains images of 338 “peculiar galaxies” — merging, overlapping and interacting galaxies. This large image is a mosaic of images in visible and infrared light taken by Hubble’s Advanced Camera for Surveys and Wide Field and Planetary Camera 2. *Image: NASA, ESA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/heic1213a.jpg)\]* *Caption: [Space Telescope Science Institute](http://www.spacetelescope.org/news/heic1213/)*
ESO/Yuri Beletsky109sept-5-2012
Shooting the Milky Way ---------------------- On the night of 21 July, ESO astronomer Yuri Beletsky took images of the night sky above Paranal, the 2600m high mountain in the Chilean Atacama Desert home to ESO's Very Large Telescope. The amazing images bear witness to the unique quality of the sky, revealing not only the Milky Way in all its splendour but also the planet Jupiter and the laser beam used at Yepun, one of the 8.2-m telescopes that make up this extraordinary facility. "The images are not composite", emphasises Yuri Beletsky. "The camera was being tracked on the stars, which can be easily noticed if you look at the telescope domes on the image (they look a little fuzzy). The colour of the laser beam on the first image actually looks pretty close to what one can see on the sky with the unaided eye." Most striking in the images is the wide band of stars called the Milky Way. Spanning more than 100 degrees in the first of these images, it shows the dust and stars that are part of our own Galaxy, a spiral galaxy containing about 100 billion stars. In the middle of this image, two bright objects are also seen. The brighter of the two is the planet Jupiter. The other is the bright star Antares. Another bright star, Alpha Centauri, one of the closest stellar neighbours to the Sun, is visible at the middle-left edge of the image. Three of the four domes that shelter the 8.2-m VLT's Unit Telescopes are visible on the first image. Streaming out of Yepun, Unit Telescope number 4, is the laser beam used to create an artificial star above Paranal, aiming directly at the centre of our own Galaxy. At the time the pictures were taken, astronomers were indeed using the SINFONI instrument to study the Galactic Centre, having a close look at the supermassive black hole that lurks in there. With so many stars visible from the exceptional site of Paranal, one may wonder why it is necessary to create another, artificial, star? The answer lies in the very sophisticated instruments that are used on ESO's VLT. Some of them, such as NACO and SINFONI, make use of adaptive optics, a technique that allows astronomers to overcome the blurring effect of the atmosphere. This means that astronomers obtain images almost as good as if the whole telescope was placed in space, above Earth's atmosphere. Adaptive optics, however, requires a nearby reference star that has to be relatively bright, thereby limiting the area of the sky that can be surveyed. To surmount this limitation, astronomers no
110sept-4-2012
Runaway Star ------------ A runaway star, plowing through the depths of space and piling up interstellar material before it, can be seen in this ultraviolet image from NASA's Galaxy Evolution Explorer. The star, called CW Leo, is hurtling through space at about 204,000 miles per hour (91 kilometers per second), or roughly 265 times the speed of sound on Earth. It is shedding its own atmosphere to form a sooty shell of discarded material. This shell can be seen in the center of this image as a bright circular blob. CW Leo is moving from right to left in this image. It is travelling so quickly through the surrounding material that it has formed a semi-circular bow shock in front of itself, like a boat moving through water. This bow shock is made of superheated gas, which flows around the star and is left behind in its turbulent wake. This blown-out bubble is 2.7 light-years across, which is more than half the distance from our sun to the nearest star, or 2,100 times the size of Pluto's orbit. The size of the bubble (called the "astrosheath") has allowed astronomers to estimate that CW Leo has been shedding its atmosphere for about 70,000 years. This is part of the star's natural life cycle as it runs out of hydrogen fuel and gradually throws off its outer layers to expose its bare, dying core. This core is called a white dwarf, and is the end product of all low-mass stars like our sun. CW Leo is the second runaway star to be observed with the Galaxy Evolution Explorer. The first, Mira, was observed by the telescope back in 2006. This image is the combination of near-ultraviolet data, shown in yellow, and far-ultraviolet data, shown in blue. For information about the Galaxy Evolution Explorer, go to: http://www.galex.caltech.edu. *Image: NASA/JPL-Caltech \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA15417.jpg)\]* *Caption: [NASA](http://photojournal.jpl.nasa.gov/catalog/PIA15417)*
111aug-31-2012
Massive Stars in Carina ----------------------- Observations made with the APEX telescope in submillimetre-wavelength light reveal the cold dusty clouds from which stars form in the Carina Nebula. This site of violent star formation, which plays host to some of the highest-mass stars in our galaxy, is an ideal arena in which to study the interactions between these young stars and their parent molecular clouds. Using the LABOCA camera on the Atacama Pathfinder Experiment (APEX) telescope on the plateau of Chajnantor in the Chilean Andes, a team of astronomers led by Thomas Preibisch (Universitäts–Sternwarte München, Ludwig-Maximilians-Universität, Germany), in close cooperation with Karl Menten and Frederic Schuller (Max-Planck-Institut für Radioastronomie, Bonn, Germany), imaged the region in submillimetre light. At this wavelength, most of the light seen is the weak heat glow from cosmic dust grains. The image therefore reveals the clouds of dust and molecular gas — mostly hydrogen — from which stars may form. At -250ºC, the dust grains are very cold, and the faint glow emanating from them can only be seen at submillimetre wavelengths, significantly longer than those of visible light. Submillimetre light is, therefore, key to studying how stars form and how they interact with their parent clouds. The APEX LABOCA observations are shown here in orange tones, combined with a visible light image from the Curtis Schmidt telescope at the Cerro Tololo Interamerican Observatory. The result is a dramatic, wide-field picture that provides a spectacular view of Carina’s star formation sites. The nebula contains stars with a total mass equivalent to over 25 000 Suns, while the mass of the gas and dust clouds is that of about 140 000 Suns. However, only a fraction of the gas in the Carina Nebula is in sufficiently dense clouds to collapse and form new stars in the immediate future (in astronomical terms, meaning within the next million years). In the longer term, the dramatic effects of the massive stars already in the region on their surrounding clouds may accelerate the star formation rate. High-mass stars live for only a few million years at most (a very short lifespan compared to the ten billion years of the Sun), but they profoundly influence their environments throughout their lives. As youngsters, these stars emit strong winds and radiation that shape the clouds around them, perhaps compressing them enough to form new stars. At the ends of their lives, they are highly unstable, being prone to outbursts of stellar material until their deaths in violent supernova explosions. A prime example of these violent stars is Eta Carinae, the bright yellowish star just to the upper left of the centre of the image. It has over 100 times the mass of our Sun, and is among the most luminous stars known. Within the next million years or so, Eta Carinae will explode as a supernova, followed by yet more supernovae from other massive stars in the region. These violent explosions rip through the molecular gas clouds in their immediate surroundings, but after the shockwaves have travelled more than about ten light-years they are weaker, and may instead compress clouds that are a little further away, triggering the formation of new generations of stars. The supernovae may also produce short-lived radioactive atoms that are picked up by the collapsing clouds. There is strong evidence that similar radioactive atoms were incorporated into the cloud that collapsed to form our Sun and planets, so the Carina Nebula may provide additional insights into the creation of our own Solar System. The Carina Nebula is some 7500 light-years distant in the constellation of the same name (Carina, or The Keel). It is among the brightest nebulae in the sky because of its large population of high-mass stars. At about 150 light-years across, it is several times larger than the well-known Orion Nebula. Even though it is several times further away than the Orion Nebula, its apparent size on the sky is therefore about the same, making it also one of the largest nebulae in the sky. The 12-metre-diameter APEX telescope is a pathfinder for ALMA, the Atacama Large Millimeter/submillimeter Array, a revolutionary new telescope that ESO, together with its international partners, is building and operating, also on the Chajnantor plateau. APEX is itself based on a single prototype antenna constructed for the ALMA project, while ALMA will be an array of 54 antennas with 12-metre diameters, and an additional 12 antennas with 7-metre diameters. While ALMA will have far higher angular resolution than APEX, its field of view will be much smaller. The two telescopes are complementary: for example, APEX will find many targets across wide areas of sky, which ALMA will be able to study in great detail. *Image: ESO/APEX/T. Preibisch et al. (Submillimetre); N. Smith, University of Minnesota/NOAO/AURA/NSF (Optical) \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1145a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/news/eso1145/)*
112aug-30-2012-2
Saturn and Titan ---------------- A giant of a moon appears before a giant of a planet undergoing seasonal changes in this natural color view of Titan and Saturn from NASA's Cassini spacecraft. Titan, Saturn's largest moon, measures 3,200 miles, or 5,150 kilometers, across and is larger than the planet Mercury. Cassini scientists have been watching the moon's south pole since a vortex appeared in its atmosphere in 2012. See PIA14919 and PIA14920 to learn more about this mass of swirling gas around the pole in the atmosphere of the moon. As the seasons have changed in the Saturnian system, and spring has come to the north and autumn to the south, the azure blue in the northern Saturnian hemisphere that greeted Cassini upon its arrival in 2004 is now fading. The southern hemisphere, in its approach to winter, is taking on a bluish hue. This change is likely due to the reduced intensity of ultraviolet light and the haze it produces in the hemisphere approaching winter, and the increasing intensity of ultraviolet light and haze production in the hemisphere approaching summer. (The presence of the ring shadow in the winter hemisphere enhances this effect.) The reduction of haze and the consequent clearing of the atmosphere makes for a bluish hue: the increased opportunity for direct scattering of sunlight by the molecules in the air makes the sky blue, as on Earth. The presence of methane, which generally absorbs in the red part of the spectrum, in a now clearer atmosphere also enhances the blue. This view looks toward the northern, sunlit side of the rings from just above the ring plane. This mosaic combines six images -- two each of red, green and blue spectral filters -- to create this natural color view. The images were obtained with the Cassini spacecraft wide-angle camera on May 6, 2012, at a distance of approximately 483,000 miles (778,000 kilometers) from Titan. Image scale is 29 miles (46 kilometers) per pixel on Titan. *Image: NASA/JPL-Caltech/SSI \[[high-resolution](http://www.nasa.gov/images/content/682400main_PIA14922_full_full.jpg)\]* *Caption: [Cassini Solstice Team](http://www.nasa.gov/mission_pages/cassini/multimedia/pia14922.html)*
113aug-29-2012
White Cosmic Dust ----------------- Like dust bunnies that lurk in corners and under beds, surprisingly complex loops and blobs of cosmic dust lie hidden in the giant elliptical galaxy NGC 1316. This image made from data obtained with the NASA Hubble Space Telescope reveals the dust lanes and star clusters of this giant galaxy that give evidence that it was formed from a past merger of two gas-rich galaxies. The combination of Hubble's superb spatial resolution and the sensitivity of the Advanced Camera for Surveys (ACS), installed onboard Hubble in 2002 and used for these images, enabled uniquely accurate measurements of a class of red star clusters in NGC 1316. Astronomers conclude that these star clusters constitute clear evidence of the occurrence of a major collision of two spiral galaxies that merged together a few billion years ago to shape NGC 1316 as it appears today. NGC 1316 is on the outskirts of a nearby cluster of galaxies in the southern constellation of Fornax, at a distance of about 75 million light-years. It is one of the brightest ellipticals in the Fornax galaxy cluster. NGC 1316, also known as Fornax A, is one of the strongest and largest radio sources in the sky, with radio lobes extending over several degrees of sky (well off the Hubble image). NGC 1316's violent history is evident in various ways. Wide-field imagery from Cerro Tololo Interamerican Observatory in Chile shows a bewildering variety of ripples, loops and plumes immersed in the galaxy's outer envelope. Amongst these so-called "tidal" features, the narrow ones are believed to be the stellar remains of other spiral galaxies that merged with NGC 1316 some time during the last few billion years. The inner regions of the galaxy shown in the Hubble image reveal a complicated system of dust lanes and patches. These are thought to be the remains of the interstellar medium associated with one or more of the spiral galaxies swallowed by NGC 1316. The U.S. team of scientists, led by Dr. Paul Goudfrooij of the Space Telescope Science Institute in Baltimore, Maryland, used the ACS onboard Hubble to study star clusters in several nearby giant elliptical galaxies. Their study of NGC 1316 focused on globular clusters, which are compact stellar systems with hundreds of thousands to millions of stars formed at the same time. The unprecedented sensitivity of the Hubble ACS data permitted the team to detect faint globular clusters previously impossible to reach. By counting the number of globular clusters detected as a function of their brightness they could, for the first time, see evidence of the gradual disruption of star clusters created during a past merger of gas-rich galaxies. They found that the relative number of low-mass clusters is significantly lower in the inner regions than in the outer regions, by an amount consistent with theoretical predictions. These Hubble ACS images were taken in March 2003. The color composite is a combination of data taken in F435W (blue), F555W (yellow-green), and F814W (infrared) filters. The team's results have improved our understanding of how elliptical galaxies and their star clusters may have formed during galaxy mergers and then evolve to resemble 'normal' elliptical galaxies after several billions of years. *Image: NASA, ESA, and The Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2005-11-a-print.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2005/11/image/a/)*
114aug-28-2012
Solar Light Bulb ---------------- At the onset of a series of coronal mass ejections (CMEs) on August 20, 2012, this bulbous CME certainly resembled a light bulb. It has the thin outer edge and a bright, glowing core at its center. CMEs are often bulbous, but it has been years since we’ve seen one with the elements (pun intended) of a light bulb. The frames were taken by Solar and Heliospheric Observatory's (SOHO) Large Angle and Spectrometric Coronagraph (LASCO) C2 instrument. LASCO is able to take images of the solar corona by blocking the light coming directly from the Sun with an occulter disk, creating an artificial eclipse within the instrument itself. The position of the solar disk is indicated in the images by the white circle. The C2 image shows the inner solar corona up to 8.4 million kilometers (5.25 million miles) away from the Sun. *Image: SOHO (ESA & NASA) \[[high-resolution](www.nasa.gov/mov/680657main_Aug20-CME.mov)\]* *Caption: [Steele Hill, Susan Hendrix, Holly Zell/NASA Goddard Space Flight Center](http://www.nasa.gov/mission_pages/sunearth/news/News082412-lightbulb.html)*
115aug-27-2012
Dune Migration -------------- This image shows large sand dunes in the North Polar sand sea on Mars. It is one of a series of repeat images of the same dunes, taken at different times, in order to determine the type and extent of changes in the dunes over time. Dunes tend to migrate slowly on Earth under continuous wind regimes (on the order of several to tens of meters per year), and we are just starting to verify movement on Martian dunes with these repeat HiRISE images. In addition to migration of the dune, we will also use these repeat images to look for changes in the dune shape and avalanches down the slip face. Analyzing these changes will help us better understand the interaction between the atmosphere and the surface of Mars. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2880/ESP_028020_2560.jpg)\]* *Caption: [HiRISE/Dan Berman](http://hirise.lpl.arizona.edu/ESP_028020_2560)*
116aug-24-2012
Young Star Cavity ----------------- In this unusual image, NASA's Hubble Space Telescope captures a rare view of the celestial equivalent of a geode — a gas cavity carved by the stellar wind and intense ultraviolet radiation from a hot young star. Real geodes are baseball-sized, hollow rocks that start out as bubbles in volcanic or sedimentary rock. Only when these inconspicuous round rocks are split in half by a geologist, do we get a chance to appreciate the inside of the rock cavity that is lined with crystals. In the case of Hubble's 35 light-year diameter "celestial geode" the transparency of its bubble-like cavity of interstellar gas and dust reveals the treasures of its interior. The object, called N44F, is being inflated by a torrent of fast-moving particles (called a "stellar wind") from an exceptionally hot star once buried inside a cold dense cloud. Compared with our Sun (which is losing mass through the so-called "solar wind"), the central star in N44F is ejecting more than a 100 million times more mass per second. The hurricane of particles moves much faster at about 4 million miles per hour (7 million kilometers per hour), as opposed to about 0.9 million miles per hour (1.5 million kilometers per hour) for our Sun. Because the bright central star does not exist in empty space but is surrounded by an envelope of gas, the stellar wind collides with this gas, pushing it out, like a snowplow. This forms a bubble, whose striking structure is clearly visible in the crisp Hubble image. The nebula N44F is one of a handful of known interstellar bubbles. Bubbles like these have been seen around evolved massive stars (Wolf-Rayet stars), and also around clusters of stars (where they are called "super-bubbles"). But they have rarely been viewed around isolated stars, as is the case here. On closer inspection N44F harbors additional surprises. The interior wall of its gaseous cavity is lined with several four- to eight-light-year-high finger-like columns of cool dust and gas. (The structure of these "columns" is similar to the Eagle Nebula's iconic "pillars of creation" photographed by Hubble a decade ago, and is seen in a few other nebulae as well). The fingers are created by a blistering ultraviolet radiation from the central star. Like windsocks caught in a gale, they point in the direction of the energy flow. These pillars look small in this image only because they are much farther away from us than the Eagle Nebula's pillars. N44F is located about 160,000 light-years in our neighboring dwarf galaxy the Large Magellanic Cloud, in the direction of the southern constellation Dorado. N44F is part of the larger N44 complex, which is a large super-bubble, blown out by the combined action of stellar winds and multiple supernova explosions. N44 itself is roughly 1,000 light-years across. Several compact star-forming regions, including N44F, are found along the rim of the central super-bubble. This image was taken with Hubble's Wide Field Planetary Camera 2 in March 2002, using filters that isolate light emitted by sulfur (shown in blue, a 1,200-second exposure) and hydrogen gas (shown in red, a 1,000-second exposure). *Image: NASA, ESA, Y. Nazé (University of Liège, Belgium) and Y.-H. Chu (University of Illinois, Urbana) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2004-26-a-full_jpg.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2004/26/image/a/)*
117aug-23-2012
Landing on Titan ---------------- This poster shows a flattened (Mercator) projection of the view from the descent imager/spectral radiometer on the European Space Agency's Huygens probe at four different altitudes. The images were taken on Jan. 14, 2005. The Huygens probe was delivered to Saturn's moon Titan by the Cassini spacecraft, which is managed by NASA's Jet Propulsion Laboratory, Pasadena, Calif. NASA supplied two instruments on the probe, the descent imager/spectral radiometer and the gas chromatograph mass spectrometer. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The descent imager/spectral radiometer team is based at the University of Arizona, Tucson. *Image: ESA/NASA/JPL/University of Arizona \[[high-resolution](http://photojournal.jpl.nasa.gov/figures/PIA08427_fig1.jpg)\]* *Caption: [Cassini Solstice Team](http://photojournal.jpl.nasa.gov/catalog/PIA08427)*
118aug-22-2012
Double Black Hole ----------------- Evidence for a pair of supermassive black holes in a spiral galaxy has been found in data from NASA's Chandra X-ray Observatory. This main image is a composite of X-rays from Chandra (blue) and optical data from the Hubble Space Telescope (gold) of the spiral galaxy NGC 3393. Meanwhile, the inset box shows the central region of NGC 3993 as observed just by Chandra. The diffuse blue emission in the large image is from hot gas near the center of NGC 3393 and shows low energy X-rays. The inset shows only high energy X-rays, including emission from iron. This type of emission is a characteristic feature of growing black holes that are heavily obscured by dust and gas. Two separate peaks of X-ray emission (roughly at 11 o'clock and 4 o'clock) can clearly be seen in the inset box. These two sources are black holes that are actively growing, generating X-ray emission as gas falls towards the black holes and becomes hotter. The obscured regions around both black holes block the copious amounts of optical and ultraviolet light produced by infalling material. At a distance of 160 million light years, NGC 3393 contains the nearest known pair of supermassive black holes. It is also the first time a pair of black holes has been found in a spiral galaxy like our Milky Way. Separated by only 490 light years, the black holes in NGC 3393 are likely the remnant of a merger of two galaxies of unequal mass a billion or more years ago. Dubbed "minor mergers" by scientists, such collisions of one larger and another smaller galaxy may, in fact, be the most common way for black hole pairs to form. Until the latest Chandra observations of NGC 3393, however, it has has been difficult to find good candidates for minor mergers because the merged galaxy is expected to look like an ordinary spiral galaxy. If this was a minor merger, the black hole in the smaller galaxy should have had a smaller mass than the other black hole before their host galaxies started to collide. Good estimates of the masses of both black holes are not yet available to test this idea, although the observations do show that both black holes are more massive than about a million Suns. *Image: X-ray: NASA/CXC/SAO/G.Fabbiano et al; Optical: NASA/STScI \[[high-resolution](http://chandra.harvard.edu/photo/2011/n3393/n3393.jpg)\]* *Caption: [Chandra X-ray Observatory](http://chandra.harvard.edu/photo/2011/n3393/)*
119aug-21-2012
Mercury Mosaic -------------- This image is a portion of the MDIS global mosaic basemap that was acquired during MESSENGER's first year in orbit around Mercury. The scene, with north to the right, shows a geological feature termed Victoria Rupes — a long cliff or scarp that formed when Mercury shrank slightly as its core cooled. Rupes on Mercury are named for ships of discovery, and Victoria Rupes is named for the Victoria that formed part of Ferdinand Magellan's fleet in his 1519-1522 effort to circumnavigate Earth. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://www.nasa.gov/images/content/641514main_messenger_orbit_image20120423_1_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/messenger/multimedia/messenger_orbit_image20120423_1.html)*
120aug-20-2012
Southern Tapestry ----------------- This magnificent view of the region around the star R Coronae Australis was created from images taken with the Wide Field Imager (WFI) at ESO’s La Silla Observatory in Chile. R Coronae Australis lies at the heart of a nearby star-forming region and is surrounded by a delicate bluish reflection nebula embedded in a huge dust cloud. The image reveals surprising new details in this dramatic area of sky. The star R Coronae Australis lies in one of the nearest and most spectacular star-forming regions. This portrait was taken by the Wide Field Imager (WFI) on the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. The image is a combination of twelve separate pictures taken through red, green and blue filters. This image shows a section of sky that spans roughly the width of the full Moon. This is equivalent to about four light-years at the distance of the nebula, which is located some 420 light-years away in the small constellation of Corona Australis (the Southern Crown). The complex is named after the star R Coronae Australis, which lies at the centre of the image. It is one of several stars in this region that belong to the class of very young stars that vary in brightness and are still surrounded by the clouds of gas and dust from which they formed. The intense radiation given off by these hot young stars interacts with the gas surrounding them and is either reflected or re-emitted at a different wavelength. These complex processes, determined by the physics of the interstellar medium and the properties of the stars, are responsible for the magnificent colours of nebulae. The light blue nebulosity seen in this picture is mostly due to the reflection of starlight off small dust particles. The young stars in the R Coronae Australis complex are similar in mass to the Sun and do not emit enough ultraviolet light to ionise a substantial fraction of the surrounding hydrogen. This means that the cloud does not glow with the characteristic red colour seen in many star-forming regions. The huge dust cloud in which the reflection nebula is embedded is here shown in impressively fine detail. The subtle colours and varied textures of the dust clouds make this image resemble an impressionist painting. A prominent dark lane crosses the image from the centre to the bottom left. Here the visible light emitted by the stars that are forming inside the cloud is completely absorbed by the dust. These objects could only be detected by observing at longer wavelengths, by using a camera that can detect infrared radiation. R Coronae Australis itself is not visible to the unaided eye, but the tiny, tiara-shaped constellation in which it lies is easily spotted from dark sites due to its proximity on the sky to the larger constellation of Sagittarius and the rich star clouds towards the centre of our own galaxy, the Milky Way. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1027a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/news/eso1027/)*
121aug-17-2012
Colorful Remnant ---------------- This stunning false-color picture shows off the many sides of the supernova remnant Cassiopeia A. It is made up of images taken by three of NASA's Great Observatories, using three different wavebands of light. Infrared data from the Spitzer Space Telescope are colored red; visible data from the Hubble Space Telescope are yellow; and X-ray data from the Chandra X-ray Observatory are green and blue. Located 10,000 light-years away in the northern constellation Cassiopeia, Cassiopeia A is the remnant of a once massive star that died in a violent supernova explosion 325 years ago. It consists of a dead star, called a neutron star, and a surrounding shell of material that was blasted off as the star died. The neutron star can be seen in the Chandra data as a sharp turquoise dot in the center of the shimmering shell. Each Great Observatory highlights different characteristics of this celestial orb. While Spitzer reveals warm dust in the outer shell about a few hundred degrees Kelvin (80 degrees Fahrenheit) in temperature, Hubble sees the delicate filamentary structures of hot gases about 10,000 degrees Kelvin (18,000 degrees Fahrenheit). Chandra probes unimaginably hot gases, up to about 10 million degrees Kelvin (18 million degrees Fahrenheit). These extremely hot gases were created when ejected material from Cassiopeia A smashed into surrounding gas and dust. Chandra can also see Cassiopeia A's neutron star (turquoise dot at center of shell). Blue Chandra data were acquired using broadband X-rays (low to high energies); green Chandra data correspond to intermediate energy X-rays; yellow Hubble data were taken using a 900 nanometer-wavelength filter, and red Spitzer data are from the telescope's 24-micron detector. The animation begins with the false-color picture of the supernova remnant Cassiopeia A. It then pans out to show a Spitzer view of Cassiopeia A (yellow ball) and surrounding clouds of dust (reddish orange). Here, the animation flips back and forth between two Spitzer images taken one year apart. A blast of light from Cassiopeia A is seen waltzing through the dusty skies. Called an "infrared echo," this dance began when the remnant's dead star erupted, or "turned in its grave," about 50 years ago. Infrared echoes are created when a star explodes or erupts, flashing light into surrounding clumps of dust. As the light zips through the dust clumps, it heats them up, causing them to glow successively in infrared, like a chain of Christmas bulbs lighting up one by one. The result is an optical illusion, in which the dust appears to be flying outward at the speed of light. Echoes are distinct from supernova shockwaves, which are made up material that is swept up and hurled outward by exploding stars. This infrared echo is the largest ever seen, stretching more than 50 light-years away from Cassiopeia A. If viewed from Earth, the entire movie frame would take up the same amount of space as two full moons. Hints of an older infrared echo from Cassiopeia A's supernova explosion hundreds of years ago can also be seen. The earlier Spitzer image was taken on November 30, 2003, and the later, on December 2, 2004. *Image: NASA/JPL-Caltech/STScI/CXC/SAO \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA03519.jpg)\]* *Caption: [NASA/JPL](http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA03519)*
122aug-16-2012
Family Portrait --------------- The cameras of Voyager 1 on Feb. 14, 1990, pointed back toward the sun and took a series of pictures of the sun and the planets, making the first ever "portrait" of our solar system as seen from the outside. In the course of taking this mosaic consisting of a total of 60 frames, Voyager 1 made several images of the inner solar system from a distance of approximately 4 billion miles and about 32 deqrees above the ecliptic plane. Thirty-nine wide angle frames link together six of the planets of our solar system in this mosiaic. Outermost Neptune is 30 times further from the sun than Earth. Our sun is seen as the bright object in the center of the circle of frames. The wide- angle image of the sun was taken with the camera's darkest filter (a methane absorption band) and the shortest possible exposure (5 thousandths of a second) to avoid saturating the camera's vidicon tube with scattered sunlight. The sun is not large as seen from Voyager, only about one-fortieth of the diameter as seen from Earth, but is still almost 8 million times brighter than the brightest star in Earth's sky, Sirius. The result of this great brightness is an image with multiple reflections from the optics in the camera. Wide-angle images surrounding the sun also show many artifacts attributable to scattered light in the optics. These were taken through the clear filter with one second exposures. The insets show the planets magnified many times. Narrow-angle images of Earth, Venus, Jupiter, Saturn, Uranus and Neptune were acquired as the spacecraft built the wide-angle mosaic. Jupiter is larger than a narrow-angle pixel and is clearly resolved, as is Saturn with its rings. Uranus and Neptune appear larger than they really are because of image smear due to spacecraft motion during the long (15 second) exposures. From Voyager's great distance Earth and Venus are mere points of light, less than the size of a picture element even in the narrow-angle camera. Earth was a crescent only 0.12 pixel in size. Coincidentally, Earth lies right in the center of one of the scattered light rays resulting from taking the image so close to the sun. *Image: NASA \[[high-resolution](http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-solarsystem.html)\]* *Caption: [NASA](http://nssdc.gsfc.nasa.gov/photo_gallery/photogallery-solarsystem.html)*
123aug-15-2012
Birth and Death --------------- In celebration of the 17th anniversary of the launch and deployment of NASA's Hubble Space Telescope, a team of astronomers is releasing one of the largest panoramic images ever taken with Hubble's cameras. It is a 50-light-year-wide view of the central region of the Carina Nebula where a maelstrom of star birth - and death - is taking place. Hubble's view of the nebula shows star birth in a new level of detail. The fantasy-like landscape of the nebula is sculpted by the action of outflowing winds and scorching ultraviolet radiation from the monster stars that inhabit this inferno. In the process, these stars are shredding the surrounding material that is the last vestige of the giant cloud from which the stars were born. The immense nebula contains at least a dozen brilliant stars that are roughly estimated to be at least 50 to 100 times the mass of our Sun. The most unique and opulent inhabitant is the star Eta Carinae, at far left. Eta Carinae is in the final stages of its brief and eruptive lifespan, as evidenced by two billowing lobes of gas and dust that presage its upcoming explosion as a titanic supernova. The fireworks in the Carina region started three million years ago when the nebula's first generation of newborn stars condensed and ignited in the middle of a huge cloud of cold molecular hydrogen. Radiation from these stars carved out an expanding bubble of hot gas. The island-like clumps of dark clouds scattered across the nebula are nodules of dust and gas that are resisting being eaten away by photoionization. The hurricane blast of stellar winds and blistering ultraviolet radiation within the cavity is now compressing the surrounding walls of cold hydrogen. This is triggering a second stage of new star formation. Our Sun and our solar system may have been born inside such a cosmic crucible 4.6 billion years ago. In looking at the Carina Nebula we are seeing the genesis of star making as it commonly occurs along the dense spiral arms of a galaxy. The immense nebula is an estimated 7,500 light-years away in the southern constellation Carina the Keel (of the old southern constellation Argo Navis, the ship of Jason and the Argonauts, from Greek mythology). This image is a mosaic of the Carina Nebula assembled from 48 frames taken with Hubble Space Telescope's Advanced Camera for Surveys. The Hubble images were taken in the light of neutral hydrogen. Color information was added with data taken at the Cerro Tololo Inter-American Observatory in Chile. Red corresponds to sulfur, green to hydrogen, and blue to oxygen emission. *Image: NASA, ESA, N. Smith (University of California, Berkeley), and The Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/2007/16/image/a/format/xlarge_web/)\]* *Caption: [Hubble heritage team](http://hubblesite.org/newscenter/archive/releases/2007/16/image/a/)*
Spitzer Space Telescope124aug-14-2012
Dusty Neighbor -------------- This new image shows the Large Magellanic Cloud galaxy in infrared light as seen by the Herschel Space Observatory, a European Space Agency-led mission with important NASA contributions, and NASA's Spitzer Space Telescope. In the instruments' combined data, this nearby dwarf galaxy looks like a fiery, circular explosion. Rather than fire, however, those ribbons are actually giant ripples of dust spanning tens or hundreds of light-years. Significant fields of star formation are noticeable in the center, just left of center and at right. The brightest center-left region is called 30 Doradus, or the Tarantula Nebula, for its appearance in visible light. The colors in this image indicate temperatures in the dust that permeates the Cloud. Colder regions show where star formation is at its earliest stages or is shut off, while warm expanses point to new stars heating surrounding dust. The coolest areas and objects appear in red, corresponding to infrared light taken up by Herschel's Spectral and Photometric Imaging Receiver at 250 microns, or millionths of a meter. Herschel's Photodetector Array Camera and Spectrometer fills out the mid-temperature bands, shown here in green, at 100 and 160 microns. The warmest spots appear in blue, courtesy of 24- and 70-micron data from Spitzer. *Image: ESA/NASA/JPL-Caltech/STScI \[[high-resolution](http://www.spitzer.caltech.edu/uploaded_files/images/0008/5022/ssc2012-01a_ExLrg.jpg)\]* *Caption: [Spitzer space telescope](http://www.spitzer.caltech.edu/images/4872-ssc2012-01a-Dusty-Space-Cloud)*
125aug-13-2012
Ganymede Mosaic --------------- What does the largest moon in the Solar System look like? Ganymede, larger than even Mercury and Pluto, has a surface speckled with bright young craters overlying a mixture of older, darker, more cratered terrain laced with grooves and ridges. Like Earth's Moon, Ganymede keeps the same face towards its central planet, in this case Jupiter. In this historic and detailed image mosaic taken by the Galileo spacecraft that orbited Jupiter from 1995 to 2003, the colors of this planet-sized moon have been enhanced to increase surface contrasts. The violet shades extending from the top and bottom are likely due to frost particles in Ganymede's polar regions. Possible future missions to Jupiter are being proposed that can search Europa and Ganymede for deep oceans that may harbor elements thought important for supporting life. *Image: Galileo Project, DLR, JPL, NASA \[[high-resolution](http://apod.nasa.gov/apod/image/0909/ganymedeenhanced_galileo_big.jpg)\]* *Caption: [Galileo Project, DLR, JPL, NASA](http://apod.nasa.gov/apod/ap090920.html)*
126aug-10-2012
Trippy Saturn ------------- Flying over the unlit side of Saturn's rings, the Cassini spacecraft captures Saturn's glow, represented in brilliant shades of electric blue, sapphire and mint green, while the planet's shadow casts a wide net on the rings. This striking false-color mosaic was created from 25 images taken by Cassini's visual and infrared mapping spectrometer over a period of 13 hours, and captures Saturn in nighttime and daytime conditions. The visual and infrared mapping spectrometer acquires data simultaneously at 352 different wavelengths, or spectral channels. Data at wavelengths of 2.3, 3.0 and 5.1 microns were combined in the blue, green and red channels of a standard color image, respectively, to make this false-color mosaic. This image was acquired on Feb. 24, 2007, while the spacecraft was 1.58 million kilometers (1 million miles) from the planet and 34.6 degrees above the ring plane. The solar phase angle was 69.5 degrees. In this view, Cassini was looking down on the northern, unlit side of the rings, which are rendered visible by sunlight filtering through from the sunlit, southern face. On the night side (right side of image), with no sunlight, Saturn's own thermal radiation lights things up. This light at 5.1 microns wavelength (some seven times the longest wavelength visible to the human eye) is generated deep within Saturn, and works its way upward, eventually escaping into space. Thick clouds deep in the atmosphere block that light. An amazing array of dark streaks, spots, and globe-encircling bands is visible instead. Saturn's strong thermal glow at 5.1 microns even allows these deep clouds to be seen on portions of the dayside (left side), especially where overlying hazes are thin and the glint of the sun off of them is minimal. These deep clouds are likely made of ammonium hydrosulfide and cannot be seen in reflected light on the dayside, since the glint of the sun on overlying hazes and ammonia clouds blocks the view of this level. A pronounced difference in the brightness between the northern and southern hemispheres is apparent. The northern hemisphere is about twice as bright as the southern hemisphere. This is because high-level, fine particles are about half as prevalent in the northern hemisphere as in the south. These particles block Saturn's glow more strongly, making Saturn look brighter in the north. At 2.3 microns (shown in blue), the icy ring particles are highly reflecting, while methane gas in Saturn's atmosphere strongly absorbs sunlight and renders the planet very dark. At 3.0 microns (shown in green), the situation is reversed: water ice in the rings is strongly absorbing, while the planet's sunlit hemisphere is bright. Thus the rings appear blue in this representation, while the sunlit side of Saturn is greenish-yellow in color. Within the rings, the most opaque parts appear dark, while the more translucent regions are brighter. In particular, the opaque, normally-bright B ring appears here as a broad, dark band separating the brighter A (outer) and C (inner) rings. At 5.1 microns (shown in red), reflected sunlight is weak and thus light from the planet is dominated by thermal (i.e., heat) radiation that wells up from the planet's deep atmosphere. This thermal emission dominates Saturn's dark side as well as the north polar region (where the hexagon is again visible) and the shadow cast by the A and B rings. Variable amounts of clouds in the planet's upper atmosphere block the thermal radiation, leading to a speckled and banded appearance, which is ever-shifting due to the planet's strong winds. The Cassini-Huygens mission is a cooperative project of NASA, the European Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory, a division of the California Institute of Technology in Pasadena, manages the mission for NASA's Science Mission Directorate, Washington, D.C. The Cassini orbiter was designed, developed and assembled at JPL. The Visual and Infrared Mapping Spectrometer team is based at the University of Arizona, where this image was produced. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA09212.jpg)\]* *Caption: [Cassini Solstice Team](http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=2625)*
127aug-9-2012
Comet Breakup ------------- NASA's Hubble Space Telescope is providing astronomers with extraordinary views of comet 73P/Schwassmann-Wachmann 3, which is falling apart right before our eyes. Recent Hubble images have uncovered many more fragments than have been reported by ground-based observers. These observations provide an unprecedented opportunity to study the demise of a comet nucleus. Amateur and professional astronomers around the world have been tracking for years the spectacular disintegration of 73P/Schwassmann-Wachmann 3. As it plunges toward a June 6th swing around the Sun, the comet will pass Earth on May 12th, at a distance of 7.3 million miles, or 30 times the distance between Earth and the Moon. The comet is currently comprised of a chain of over three dozen separate fragments, named alphabetically, stretching across several degrees on the sky. (The Sun and Moon each have an apparent diameter of about 1/2 of a degree.) Ground-based observers have noted dramatic brightening events associated with some of the fragments (as shown in the bottom frame) indicating that they are continuing to break-up and that some may disappear altogether. Hubble caught two of the fragments, B and G, (top frames) shortly after large outbursts in activity. Hubble also photographed fragment C (not shown), which was less active. The resulting images reveal that a hierarchical destruction process is taking place, in which fragments are continuing to break into smaller chunks. Several dozen "mini-fragments" are found trailing behind each main fragment, probably associated with the ejection of house-sized chunks of surface material that can only be detected in these very sensitive and high-resolution Hubble images. Sequential Hubble images of the B fragment, taken a few days apart, suggest that the chunks are pushed down the tail by outgassing from the icy, sunward-facing surfaces of the chunks, much like space-walking astronauts are propelled by their jetpacks. The smaller chunks have the lowest mass, and so are accelerated away from the parent nucleus faster than the larger chunks. Some of the chunks seem to dissipate completely over the course of several days. Deep-freeze relics of the early solar system, cometary nuclei are porous and fragile mixes of dust and ices. They can be broken apart by gravitational tidal forces when they pass near large bodies (for example, Comet Shoemaker-Levy 9 was torn to pieces when it skirted near Jupiter in 1992, prior to plunging into Jupiter's atmosphere two years later). They can also fly apart from rapid rotation of the nucleus, break apart because of thermal stresses as they pass near the Sun, or explosively pop apart like corks from champagne bottles due to the outburst of trapped volatile gases. "Catastrophic breakups may be the ultimate fate of most comets," says planetary astronomer Hal Weaver of the Johns Hopkins University Applied Physics Laboratory, who led the team that made the recent Hubble observations and who used Hubble previously to study the fragmentations of comets Shoemaker-Levy 9 in 1993-1994, Hyakutake in 1996, and 1999 S4 (LINEAR) in 2000. Analysis of the new Hubble data, and data taken by other observatories as the comet approaches the Earth and Sun, may reveal which of these breakup mechanisms are contributing to the disintegration of 73P/Schwassmann-Wachmann 3. German astronomers Arnold Schwassmann and Arno Arthur Wachmann discovered this comet during a photographic search for asteroids in 1930, when the comet passed within 5.8 million miles of the Earth (only 24 times the Earth-Moon distance). The comet orbits the Sun every 5.4 years, but it was not seen again until 1979. The comet was missed again in 1985 but has been observed every return since then. During the fall of 1995, the comet had a huge outburst in activity and shortly afterwards four separate nuclei were identified and labeled "A", "B", "C", and "D", with "C" being the largest and the presumed principal remnant of the original nucleus. Only the C and B fragments were definitively observed during the next return, possibly because of the poor geometry for the 2000-2001 apparition. The much better observing circumstances during this year's return may be partly responsible for the detection of so many new fragments, but it is also likely that the disintegration of the comet is now accelerating. Whether any of the many fragments will survive the trip around the Sun remains to be seen. *Image: NASA, ESA, H. Weaver (JHU/APL), M. Mutchler and Z. Levay (STScI) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2006-18-a-print.jpg)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2006/18/image/a/)*
NASA/JPL-Caltech128aug-8-2012
Swirling Galaxy --------------- The galaxy Messier 100, or M100, shows its swirling spiral in this infrared image from NASAs Spitzer Space Telescope. The arcing spiral arms of dust and gas that harbor starforming regions glow vividly when seen in the infrared. M100 is a classic example of a grand design spiral galaxy, with prominent and well-defined spiral arms winding from the hot center, out to the cooler edges of the galaxy. It is located about 55 million light years away from Earth, in the little-known constellation of Coma Berenices, near to the more recognizable Leo. In the center, we can see a prominent ring of hot, bright dust surrounding the inner galactic core. Moving further out, the spiral arms peter out towards the edges of the galaxy, where thick webs of dust dominate. Beyond the edges of the dust clouds, a faint blue glow of stars extends to the edge of the galaxys disk. Two small companion galaxies, known as NGC 4323 and NGC 4328, appear as fuzzy blue blobs on the upper side of M100. These so-called lenticular galaxies are virtually clear of any dust, so they lack any of the red/green glow seen in their bigger neighbor. The shape of M100 is probably being perturbed by the gravity of these galaxies. M100 was discovered in 1781, and is now known to stretch roughly 160,000 light years from one side to the other, making it about one and a half times the size of our own Milky Way galaxy. By studying these infrared images of M100, astronomers can map out the structure of the stars and dust, and study the ways in which galaxies like our Milky Way were formed. M100 is well-known to astronomers because of the five stars that have become supernovae within the galaxy between 1901 and 2006. These exploding stars are extremely useful for helping astronomers to calibrate distance scales in the universe, and to estimate the age of the universe since its creation in the Big Bang. The green regions reveal dust clouds that light up under the illumination of the surrounding stars. The longer infrared wavelengths, which trace the thermal glow of the hottest dust, are overlaid in red. This gives the areas of strongest star formation a reddish/white glow; this is particularly strong in the central ring. The stars themselves shine most brightly at the shorter infrared wavelengths, showing up here in blue. The blue dots covering the entire image are stars that lie between us and M100. Infrared light with wavelengths of 3.6 and 4.5 microns is shown as blue/cyan, showing primarily the glow from starlight. 8 micron light is rendered in green, and 24 micron emission is red, tracing the cooler and warmer components of dust, respectively. *Image: NASA/JPL-Caltech \[[high-resolution](http://www.spitzer.caltech.edu/uploaded_files/images/0009/0061/sig12-008.jpg)\]* *Caption: [Spitzer Space Telescope](http://www.spitzer.caltech.edu/images/5212-sig12-008-Hot-and-Cold-in-the-M100-Galaxy-)*
129aug-7-2012
Tarantula Details ----------------- Turning its 2.4-metre eye to the Tarantula Nebula, the NASA/ESA Hubble Space Telescope has taken this close-up of the outskirts of the main cloud of the Nebula. The bright wispy structures are the signature of an environment rich in ionised hydrogen gas, called H II by astronomers. In reality these appear red, but the choice of filters and colours of this image, which includes exposures both in visible and infrared light, make the gas appear green. These regions contain recently formed stars, which emit powerful ultraviolet radiation that ionises the gas around them. These clouds are ephemeral as eventually the stellar winds from the newborn stars and the ionisation process will blow away the clouds, leaving stellar clusters like the Pleiades. Located in the Large Magellanic Cloud, one of our neighbouring galaxies, and situated at a distance of 170 000 light-years away from Earth, the Tarantula Nebula is the brightest known nebula in the Local Group of galaxies. It is also the largest (around 650 light-years across) and most active star-forming region known in our group of galaxies, containing numerous clouds of dust and gas and two bright star clusters. A recent Hubble image shows a large part of the nebula immediately adjacent to this field of view. The cluster at the Tarantula nebula’s centre is relatively young and very bright. While it is outside the field of view of this image, the energy from it is responsible for most of the brightness of the Nebula, including the part we see here. The nebula is in fact so luminous that if it were located within 1000 light-years from Earth, it would cast shadows on our planet. The Tarantula Nebula was host to the closest supernova ever detected since the invention of the telescope, supernova 1987A, which was visible to the naked eye. The image was produced by Hubble’s Advanced Camera for Surveys, and has a field of view of approximately 3.3 by 3.3 arcminutes. A version of this image was entered into the Hubble’s Hidden Treasures Image Processing Competition by contestant Judy Schmidt. Hidden Treasures is an initiative to invite astronomy enthusiasts to search the Hubble archive for stunning images that have never been seen by the general public. The competition has now closed and the results will be published soon. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/screen/potw1232a.jpg)\]* *Caption: [Hubble Heritage Team](http://www.spacetelescope.org/images/potw1232a/)*
130aug-6-2012
Curiosity's Landing Spot ------------------------ As of June 2012, the target landing area for NASA's Mars Science Laboratory mission is the ellipse marked on this image of Gale Crater. The ellipse is about 12 miles long and 4 miles wide (20 kilometers by 7 kilometers). This view of Gale Crater is derived from a combination of data from three Mars orbiters. The view is looking straight down on the crater from orbit. Gale Crater is 96 miles (154 kilometers) in diameter. Mount Sharp rises about 3.4 miles (5.5 kilometers) above the floor of Gale Crater. Stratification on Mount Sharp suggests the mountain is a surviving remnant of an extensive series of deposits that were laid down after a massive impact that excavated Gale Crater more than 3 billion years ago. The layers offer a history book of sequential chapters recording environmental conditions when each stratum was deposited. During a prime mission lasting nearly two years after landing, Curiosity will use 10 instruments to investigate whether this area of Mars has ever offered conditions favorable for life, including the chemical ingredients for life. The image combines elevation data from the High Resolution Stereo Camera on the European Space Agency's Mars Express orbiter, image data from the Context Camera on NASA's Mars Reconnaissance Orbiter, and color information from Viking Orbiter imagery. *Image: NASA/JPL-Caltech/ESA/DLR/FU Berlin/MSSS \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA15687.jpg)\]* *Caption: [NASA/JPL](http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA15687)*
131aug-3-2012
Red Space Ribbon ---------------- A delicate ribbon of gas floats eerily in our galaxy. A contrail from an alien spaceship? A jet from a black-hole? Actually this image, taken by NASA's Hubble Space Telescope, is a very thin section of a supernova remnant caused by a stellar explosion that occurred more than 1,000 years ago. On or around May 1, 1006 A.D., observers from Africa to Europe to the Far East witnessed and recorded the arrival of light from what is now called SN 1006, a tremendous supernova explosion caused by the final death throes of a white dwarf star nearly 7,000 light-years away. The supernova was probably the brightest star ever seen by humans, and surpassed Venus as the brightest object in the night time sky, only to be surpassed by the moon. It was visible even during the day for weeks, and remained visible to the naked eye for at least two and a half years before fading away. It wasn't until the mid-1960s that radio astronomers first detected a nearly circular ring of material at the recorded position of the supernova. The ring was almost 30 arcminutes across, the same angular diameter as the full moon. The size of the remnant implied that the blast wave from the supernova had expanded at nearly 20 million miles per hour over the nearly 1,000 years since the explosion occurred. In 1976, the first detection of exceedingly faint optical emission of the supernova remnant was reported, but only for a filament located on the northwest edge of the radio ring. A tiny portion of this filament is revealed in detail by the Hubble observation. The twisting ribbon of light seen by Hubble corresponds to locations where the expanding blast wave from the supernova is now sweeping into very tenuous surrounding gas. The hydrogen gas heated by this fast shock wave emits radiation in visible light. Hence, the optical emission provides astronomers with a detailed "snapshot" of the actual position and geometry of the shock front at any given time. Bright edges within the ribbon correspond to places where the shock wave is seen exactly edge on to our line of sight. Today we know that SN 1006 has a diameter of nearly 60 light-years, and it is still expanding at roughly 6 million miles per hour. Even at this tremendous speed, however, it takes observations typically separated by years to see significant outward motion of the shock wave against the grid of background stars. In the Hubble image as displayed, the supernova would have occurred far off the lower right corner of the image, and the motion would be toward the upper left. SN 1006 resides within our Milky Way Galaxy. Located more than 14 degrees off the plane of the galaxy's disk, there is relatively little confusion with other foreground and background objects in the field when trying to study this object. In the Hubble image, many background galaxies (orange extended objects) far off in the distant universe can be seen dotting the image. Most of the white dots are foreground or background stars in our Milky Way galaxy. This image is a composite of hydrogen-light observations taken with Hubble's Advanced Camera for Surveys in February 2006 and Wide Field Planetary Camera 2 observations in blue, yellow-green, and near-infrared light taken in April 2008. The supernova remnant, visible only in the hydrogen-light filter was assigned a red hue in the Heritage color image. *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/2008/22/image/a/format/xlarge_web/)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2008/22/image/a/)*
132aug-2-2012
Peeping Moon ------------ Saturn's moon Mimas peeps out from behind the larger moon Dione in this view from the Cassini spacecraft. Mimas (246 miles, or 396 kilometers across) is near the bottom center of the image. Saturn's rings are also visible in the top right. This view looks toward the anti-Saturn side of Dione (698 miles, or 1,123 kilometers across). North on Dione is up and rotated 20 degrees to the right. This view looks toward the northern, sunlit side of the rings from just above the ringplane. The image was taken in visible light with the Cassini spacecraft narrow-angle camera on Dec. 12, 2011. The view was obtained at a distance of approximately 377,000 miles (606,000 kilometers) from Mimas. The view was obtained at a distance of approximately 56,000 miles (91,000 kilometers) from Dione and at a Sun-Dione-spacecraft, or phase, angle of 42 degrees. Image scale is 1,773 feet (541 meters) per pixel on Dione. *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA14619.jpg)\]* *Caption: [Cassini Solstice Team](http://photojournal.jpl.nasa.gov/catalog/PIA14619)*
133aug-1-2012
Blue Dunes of Mars ------------------ HiRISE has been carrying out a dedicated survey of sand dunes on Mars, determining whether and how fast the dunes move by observing repeatedly at intervals of Martian years. More than 60 sites have been monitored so far, showing that sand dunes from the equator to the poles are advancing at rates of up to 1 meter per Martian year. These observations are still spotty, however, and tend to be concentrated in the tropics and the North Polar erg (the sand sea that surrounds the North Pole). One latitude band that had not been sampled at all lies between 30 and 65 degrees north. This observation is among a set of images acquired to fill that gap. This image shows a variety of different dune types in southern Lyot Crater in the Northern lowlands at 48.9 degrees north. Transverse dunes to the west grade into longitudinal dunes downwind to the east and barchans to the south, possibly because of local winds channeled by topography in the impact basin. This image was intended to match the approximate illumination and viewing conditions of an earlier HiRISE observation that was made two Martian years earlier, in August 2008. Detailed comparison of the two images shows movement on many of the dunes during this interval of nearly four Earth years. The subimage is an animation showing changes on one of the small barchans in the south of the dune field. The area pictured in the subimage is about 100 meters across. Winds from the west (left) have shifted the small ripples up the back of the dune towards the east. Sand has blown over the crest of the dune, cascaded down the steep slip face, and accumulated along the base of the slip face in the lee of the dune. In this way, the small dune advances slowly downwind. Other images also show dune activity in this latitude band, adding to a growing suspicion that dunes are on the move everywhere on Mars, faster in some places than others. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2880/ESP_027864_2295.jpg)\]* *Caption: [Paul Geissler](http://hirise.lpl.arizona.edu/ESP_027864_2295)*
ESO134jul-31-2012
Heart-Shaped Nebula ------------------- Area surrounding the stellar cluster NGC 2467, located in the southern constellation of Puppis ("The Stern"). With an age of a few million years at most, it is a very active stellar nursery, where new stars are born continuously from large clouds of dust and gas. The image, looking like a colourful cosmic ghost or a gigantic celestial Mandrill, contains the open clusters Haffner 18 (centre) and Haffner 19 (middle right: it is located inside the smaller pink region — the lower eye of the Mandrill), as well as vast areas of ionised gas. The bright star at the centre of the largest pink region on the bottom of the image is HD 64315, a massive young star that is helping shaping the structure of the whole nebular region. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso0544a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0544a/)*
135jul-30-2012
Messier 68 ---------- The NASA/ESA Hubble Space Telescope offers this delightful view of the crowded stellar encampment called Messier 68, a spherical, star-filled region of space known as a globular cluster. Mutual gravitational attraction amongst a cluster’s hundreds of thousands or even millions of stars keeps stellar members in check, allowing globular clusters to hang together for many billions of years. Astronomers can measure the ages of globular clusters by looking at the light of their constituent stars. The chemical elements leave signatures in this light, and the starlight reveals that globular clusters' stars typically contain fewer heavy elements, such as carbon, oxygen and iron, than stars like the Sun. Since successive generations of stars gradually create these elements through nuclear fusion, stars having fewer of them are relics of earlier epochs in the Universe. Indeed, the stars in globular clusters rank among the oldest on record, dating back more than 10 billion years. More than 150 of these objects surround our Milky Way galaxy. On a galactic scale, globular clusters are indeed not all that big. In Messier 68's case, its constituent stars span a volume of space with a diameter of little more than a hundred light-years. The disc of the Milky Way, on the other hand, extends over some 100 000 light-years or more. Messier 68 is located about 33 000 light-years from Earth in the constellation Hydra (The Female Water Snake). French astronomer Charles Messier notched the object as the sixty-eighth entry in his famous catalogue in 1780. Hubble added Messier 68 to its own impressive list of cosmic targets in this image using the Wide Field Camera of Hubble’s Advanced Camera for Surveys. The image, which combines visible and infrared light, has a field of view of approximately 3.4 by 3.4 arcminutes. *Image: ESA/Hubble & NASA \[[high-resolution](http://www.spacetelescope.org/static/archives/images/large/potw1231a.jpg)\]* *Caption: [NASA/ESA](http://www.spacetelescope.org/images/potw1231a/)*
136jul-27-2012
Venus Revealed -------------- This global view of the surface of Venus is centered at 180 degrees east longitude. Magellan synthetic aperture radar mosaics from the first cycle of Magellan mapping are mapped onto a computer-simulated globe to create this image. Data gaps are filled with Pioneer Venus Orbiter data, or a constant mid-range value. Simulated color is used to enhance small-scale structure. The simulated hues are based on color images recorded by the Soviet Venera 13 and 14 spacecraft. The image was produced by the Solar System Visualization project and the Magellan science team at the JPL Multimission Image Processing Laboratory and is a single frame from a video released at the October 29, 1991, JPL news conference. *Image: NASA/JPL \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA00104.jpg)\]* *Caption: [NASA](http://photojournal.jpl.nasa.gov/catalog/PIA00104)*
137jul-26-2012
El Gordo -------- This picture of the galaxy cluster ACT-CL J0102−4915 combines images taken with ESO’s Very Large Telescope with images from the SOAR Telescope and X-ray observations from NASA’s Chandra X-ray Observatory. The X-ray image shows the hot gas in the cluster and is shown in blue. This newly discovered galaxy cluster has been nicknamed El Gordo — the "big" or "fat one" in Spanish. It consists of two separate galaxy subclusters colliding at several million kilometres per hour, and is so far away that its light has travelled for seven billion years to reach the Earth. *Image: X-ray: ESO/SOAR/NASA \[[high-resolution](http://www.eso.org/public/archives/images/large/eso1203a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso1203a/)*
138jul-25-2012
Red Europa ---------- This enhanced color image of the region surrounding the young impact crater Pwyll on Jupiter's moon Europa was produced by combining low resolution color data with a higher resolution mosaic of images obtained on December 19, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. This region is on the trailing hemisphere of the satellite, centered at 11 degrees South and 276 degrees West, and is about 1240 kilometers across. North is toward the top of the image, and the sun illuminates the surface from the east. The 26 kilometer diameter impact crater Pwyll, just below the center of the image, is thought to be one of the youngest features on the surface of Europa. The diameter of the central dark spot, ejecta blasted from beneath Europa's surface, is approximately 40 kilometers, and bright white rays extend for over a thousand kilometers in all directions from the impact site. These rays cross over many different terrain types, indicating that they are younger than anything they cross. Their bright white color may indicate that they are composed of fresh, fine water ice particles, as opposed to the blue and brown tints of older materials elsewhere in the image. Also visible in this image are a number of the dark lineaments which are called "triple bands" because they have a bright central stripe surrounded by darker material. Scientists can use the order in which these bands cross each other to determine their relative ages, as they attempt to reconstruct the geologic history of Europa. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA01211.jpg)\]* *Caption: [NASA](http://photojournal.jpl.nasa.gov/catalog/PIA01211)*
Chandra X-ray Observatory Center139jul-24-2012
Fast Pulsar ----------- Researchers using three different telescopes -- NASA's Chandra X-ray Observatory and ESA's XMM-Newton in space, and the Parkes radio telescope in Australia -- may have found the fastest moving pulsar ever seen. The evidence for this potentially record-breaking speed comes, in part, from the features highlighted in this composite image. X-ray observations from Chandra (green) and XMM-Newton (purple) have been combined with infrared data from the 2MASS project and optical data from the Digitized Sky Survey (colored red, green and blue, but appearing in the image as white). The large area of diffuse X-rays seen by XMM-Newton was produced when a massive star exploded as a supernova, leaving behind a debris field, or supernova remnant known as SNR MSH 11-16A. Shocks waves from the supernova have heated surrounding gas to several million degrees Kelvin, causing the remnant to glow brightly in X-rays. *Image: X-ray: NASA/CXC/UC Berkeley/J.Tomsick et al & ESA/XMM-Newton, Optical: DSS; IR: 2MASS/UMass/IPAC-Caltech/NASA/NSF \[[high-resolution](http://chandra.harvard.edu/photo/2012/igrj11014/igrj11014_lg.jpg)\]* *Caption: [Chandra](http://chandra.harvard.edu/photo/2012/igrj11014/)*
140jul-23-2012
Rainbow Orion ------------- This new view of the Orion nebula highlights fledgling stars hidden in the gas and clouds. It shows infrared observations taken by NASA's Spitzer Space Telescope and the European Space Agency's Herschel mission, in which NASA plays an important role. A star forms as a clump of this gas and dust collapses, creating a warm glob of material fed by an encircling disk. These dusty envelopes glow brightest at longer wavelengths, appearing as red dots in this image. In several hundred thousand years, some of the forming stars will accrete enough material to trigger nuclear fusion at their cores and then blaze into stardom. The nebula is found below the three belt stars in the famous constellation of Orion the Hunter, which appears at night in northern latitudes during fall and then throughout winter. At a distance of around 1,500 light-years away from Earth, the nebula cannot quite be seen with the naked eye. Binoculars or a small telescope, however, are all it takes to get a good look in visible light at this stellar factory. Spitzer is designed to see shorter infrared wavelengths than Herschel. By combining their observations, astronomers get a more complete picture of star formation. The colors in this image relate to the different wavelengths of light, and to the temperature of material, mostly dust, in this region of Orion. Data from Spitzer show warmer objects in blue, with progressively cooler dust appearing green and red in the Herschel datasets. The more evolved, hotter embryonic stars thus appear in blue. The combined data traces the interplay of the bright, young stars with the cold and dusty surrounding clouds. A red garland of cool gas also notably runs through the Trapezium, the intensely bright region that is home to four humungous blue-white stars, and up into the rich star field. Infrared data at wavelengths of 8.0 and 24 microns from Spitzer are rendered in blue. Herschel data with wavelengths of 70 and 160 microns are represented in green and red, respectively. Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. NASA's Herschel Project Office is based at NASA's Jet Propulsion Laboratory. JPL contributed mission-enabling technology for two of Herschel's three science instruments. The NASA Herschel Science Center, part of the Infrared Processing and Analysis Center at the California Institute of Technology in Pasadena, supports the United States astronomical community. Caltech manages JPL for NASA. *Image: NASA/ESA/JPL-Caltech/IRAM \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA13959.jpg)\]* *Caption: [JPL/NASA](http://www.jpl.nasa.gov/spaceimages/details.php?id=PIA13959)*
141jul-20-2012
Hole on Mars ------------ Earlier this year, the CTX camera team saw a crater containing a dark spot on the dusty slopes of the Pavonis Mons volcano. We took a closer look at this feature with HiRISE and found this unusual geologic feature on Mars. The dark spot turned out to be a "skylight," an opening to an underground cavern, that is 35 meters (115 feet) across. Caves often form in volcanic regions like this when lava flows solidify on top, but keep flowing underneath their solid crust. These, now underground, rivers of lava can then drain away leaving the tube they flowed through empty. We can use the shadow cast on the floor of the pit to calculate that it is about 20 meters (65 feet) deep. The origin of the larger hole that this pit is within is still obscure. You can see areas where material on the walls has slid into the pit. How much of the missing material has disappeared via the pit into the underground cavern? *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2560/ESP_023531_1840.jpg)\]* *Caption: [Shane Byrne](http://hirise.lpl.arizona.edu/ESP_023531_1840)*
ESO/F. Marchis, M. Wong, E. Marchetti, P. Amico, S. Tordo142jul-19-2012
Moody Jupiter ------------- Amazing image of Jupiter taken in infrared light on the night of 17 August 2008 with the Multi-Conjugate Adaptive Optics Demonstrator (MAD) prototype instrument mounted on ESO's Very Large Telescope. This false colour photo is the combination of a series of images taken over a time span of about 20 minutes, through three different filters (2, 2.14, and 2.16 microns). The image sharpening obtained is about 90 milli-arcseconds across the whole planetary disc, a real record on similar images taken from the ground. This corresponds to seeing details about 300 km wide on the surface of the giant planet. The great red spot is not visible in this image as it was on the other side of the planet during the observations. The observations were done at infrared wavelengths where absorption due to hydrogen and methane is strong. This explains why the colours are different from how we usually see Jupiter in visible-light. This absorption means that light can be reflected back only from high-altitude hazes, and not from deeper clouds. These hazes lie in the very stable upper part of Jupiter's troposphere, where pressures are between 0.15 and 0.3 bar. Mixing is weak within this stable region, so tiny haze particles can survive for days to years, depending on their size and fall speed. Additionally, near the planet's poles, a higher stratospheric haze (light blue regions) is generated by interactions with particles trapped in Jupiter's intense magnetic field. *Image: ESO/F. Marchis, M. Wong, E. Marchetti, P. Amico, S. Tordo \[[high-resolution](http://www.eso.org/public/archives/images/large/eso0833a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0833a/)*
Chandra X-ray Observatory Center143jul-18-2012
Beautiful Pulsar ---------------- Data from NASA's Chandra X-ray Observatory and ESA's XMM-Newton have been combined to discover a young pulsar in the remains of a supernova located in the Small Magellanic Cloud, or SMC. This would be the first definite time a pulsar, a spinning, ultra-dense star, has been found in a supernova remnant in the SMC, a small satellite galaxy to the Milky Way. In this composite image, X-rays from Chandra and XMM-Newton have been colored blue and optical data from the Cerro Tololo Inter-American Observatory in Chile are colored red and green. The pulsar, known as SXP 1062, is the bright white source located on the right-hand side of the image (roll your mouse over the image above) in the middle of the diffuse blue emission inside a red shell. The diffuse X-rays and optical shell are both evidence for a supernova remnant surrounding the pulsar. The optical data also displays spectacular formations of gas and dust in a star-forming region on the left side of the image. A comparison of the Chandra image with optical images shows that the pulsar has a hot, massive companion. Astronomers are interested in SXP 1062 because the Chandra and XMM-Newton data show that it is rotating unusually slowly - about once every 18 minutes. (In contrast, some pulsars are found to revolve multiple times per second, including most newly born pulsars.) This relatively leisurely pace of SXP 1062 makes it one of the slowest rotating X-ray pulsars in the SMC. Two different teams of scientists have estimated that the supernova remnant around SXP 1062 is between 10,000 and 40,000 years old, as it appears in the image. This means that the pulsar is very young, from an astronomical perspective, since it was presumably formed in the same explosion that produced the supernova remnant. Therefore, assuming that it was born with rapid spin, it is a mystery why SXP 1062 has been able to slow down by so much, so quickly. Work has already begun on theoretical models to understand the evolution of this unusual object. *Image: X-ray: NASA/CXC/Univ.Potsdam/L.Oskinova et al & ESA/XMM-Newton; Optical: AURA/NOAO/CTIO/Univ.Potsdam/L.Oskinova et al \[[high-resolution](http://chandra.harvard.edu/photo/2011/sxp1062/sxp1062.jpg)\]* *Caption: [Chandra/Harvard](http://chandra.harvard.edu/photo/2011/sxp1062/)*
144jul-17-2012
Supernova Remnant ----------------- In the nearby galaxy known as the Small Magellanic Cloud, a massive star has exploded as a supernova and begun to dissipate its interior into a spectacular display of colorful filaments, reminiscent of fireworks display. The supernova remnant (SNR), known as "E0102" for short, is the greenish-blue shell of debris just below the center of this image from NASA's Hubble Space Telescope. This delicate structure, glowing a multitude of lavenders and peach hues, resides in the upper right of the image. Determined to be only about 2,000 years old, E0102 is relatively young on astronomical scales and is just beginning its interactions with the nearby interstellar medium. Young supernova remnants like E0102 allow astronomers to examine material from the cores of massive stars directly. This in turn gives insight on how stars form, their composition, and the chemical enrichment of the surrounding area. As well, young remnants are a great learning tool to better understand the physics of supernova explosions. The Small Magellanic Cloud is a nearby dwarf galaxy to our own Milky Way. It is visible in the Southern Hemisphere, in the direction of the constellation Tucana, and lies roughly 210,000 light-years distant. *Image: NASA, ESA, the Hubble Heritage Team (STScI/AURA) and J. Green (University of Colorado, Boulder) \[[high-resolution](http://www.nasa.gov/images/content/161524main_image_feature_684_ys_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_684.html)*
145jul-16-2012
Mars Dunes ---------- This field of crescent-shaped dunes (lat.73.62, lon. 328.215) is located just south of the North Polar layered terrain of Mars. These dunes, known as barchan dunes, usually form where there is a moderate supply of sand and a prevailing wind direction. The "arms" or "horns" of barchan dunes point in the downwind direction and in this case indicate that the prevailing winds blow towards the northwest. The dunes in the close-up image are approximately 100 meters across and are traversing a bumpy, hard terrain. Polygonal patterns are evident in some areas while numerous meter-scale boulders are strewn throughout the region. The boulders are more numerous in areas where the polygonal patterns are less pronounced. Repeat imaging of this dune field could reveal whether these dunes are presently moving. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/1152/ESP_027378_2540.jpg)\]* *Caption: [Ginny Gulick](http://hirise.lpl.arizona.edu/ESP_027378_2540)*
146jul-13-2012
Purple Black Hole ----------------- NASA's Chandra X-ray Observatory has discovered an extraordinary outburst by a black hole in the spiral galaxy M83, located about 15 million light years from Earth. Using Chandra, astronomers found a new ultraluminous X-ray source, or ULX. These objects give off more X-rays than most normal binary systems in which a companion star is in orbit around a neutron star or black hole. *Image: NASA/CXC/Curtin University/R.Soria et al. \[[high-resolution](http://www.nasa.gov/images/content/667543main_6986578034_2ff89714dd_o_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2307.html)*
147jul-12-2012
ISS and Moon ------------ This picture of the International Space Station was photographed from the space shuttle Atlantis as the orbiting complex and the shuttle performed their relative separation in the early hours of July 19, 2011. Onboard the station were Russian cosmonauts Andrey Borisenko, Expedition 28 commander; Sergei Volkov and Alexander Samokutyaev, both flight engineers; Japan Aerospace Exploration astronaut Satoshi Furukawa, and NASA astronauts Mike Fossum and Ron Garan, all flight engineers. Onboard the shuttle were NASA astronauts Chris Ferguson, STS-135 commander; Doug Hurley, pilot; and Sandy Magnus and Rex Walheim, both mission specialists. *Image: NASA \[[high-resolution](http://spaceflight.nasa.gov/gallery/images/shuttle/sts-135/hires/s135e011814.jpg)\]* *Caption: [NASA](http://spaceflight.nasa.gov/gallery/images/shuttle/sts-135/html/s135e011814.html)*
148jul-11-2012
Angelic Nebula -------------- NASA's Hubble Space Telescope presents a festive holiday greeting that's out of this world. The bipolar star-forming region, called Sharpless 2-106, looks like a soaring, celestial snow angel. The outstretched "wings" of the nebula record the contrasting imprint of heat and motion against the backdrop of a colder medium. Sharpless 2-106, Sh2-106 or S106 for short, lies nearly 2,000 light-years from us. The nebula measures several light-years in length. It appears in a relatively isolated region of the Milky Way galaxy. A massive, young star, IRS 4 (Infrared Source 4), is responsible for the furious activity we see in the nebula. Twin lobes of super-hot gas, glowing blue in this image, stretch outward from the central star. This hot gas creates the "wings" of our angel. A ring of dust and gas orbiting the star acts like a belt, cinching the expanding nebula into an "hourglass" shape. Hubble's sharp resolution reveals ripples and ridges in the gas as it interacts with the cooler interstellar medium. Dusky red veins surround the blue emission from the nebula. The faint light emanating from the central star reflects off of tiny dust particles. This illuminates the environment around the star, showing darker filaments of dust winding beneath the blue lobes. Detailed studies of the nebula have also uncovered several hundred brown dwarfs. At purely infrared wavelengths, more than 600 of these sub-stellar objects appear. These "failed" stars weigh less than a tenth of our Sun. Because of their low mass, they cannot produce sustained energy through nuclear fusion like our Sun does. They encompass the nebula in a small cluster. The Hubble images were taken in February 2011 with the Wide Field Camera 3. Visible narrow-band filters that isolate the hydrogen gas were combined with near-infrared filters that show structure in the cooler gas and dust. *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/2011/38/image/a/format/xlarge_web/)\]* *Caption: [Hubble heritage team](http://hubblesite.org/newscenter/archive/releases/2011/38/image/a/)*
149jul-10-2012
Winter is Coming ---------------- False-color images from NASA's Cassini spacecraft show the development of a hood of high-altitude haze -- which appears orange in this image -- forming over the south pole of Saturn's moon Titan. These images were obtained on May 22 and June 7, 2012 by the visual and infrared mapping spectrometer in infrared wavelengths. Scientists assigned the colors red, green and blue to wavelengths mostly sensitive to the stratosphere, troposphere, and surface components, respectively. The newly discovered feature appears several hundred miles (kilometers) above the surface. When Cassini arrived at Saturn, it saw a hood of clouds and haze over Titan's north pole, which was experiencing winter. The south pole was basically clear, except for sporadic methane clouds. The seasons have been changing and the circulation in the upper atmosphere goes now from the illuminated north pole to the cooling south pole, causing downwellings over the south pole and formation of the hood. *Image: NASA/JPL-Caltech/University of Arizona/LPGNantes \[[high-resolution](http://www.ciclops.org/view_media/36439/Winters_Coming)\]* *Caption: [Cassini Solistice Team](http://www.ciclops.org/view/7237/Winters_Coming)*
150jul-9-2012
Mars and Milky Way ------------------ This view of Mars (visible towards the top of the image) and of the Milky Way was taken by the OSRIS camera on board the Rosetta orbiter on 3 December 2006, during the last series of instrument check-outs. In this image Mars is heavily overexposed and therefore surrounded by a halo of scattered light. *Image: ESA ©2005 MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA \[[high-resolution](http://www.esa.int/images/Mars_wac_milkyway_H.jpg)\]* *Caption: [ESA](http://www.esa.int/esa-mmg/mmg.pl?b=b&keyword=phobos&single=y&start=57)*
Spitzer Space Telescope151jul-6-2012
Downtown Milky Way ------------------ The region around the center of our Milky Way galaxy glows colorfully in this new version of an image taken by NASA's Spitzer Space Telescope. The data were previously released as part of a long, 120-degree view of the plane our galaxy (see http://www.spitzer.caltech.edu/images/2680-ssc2008-11a-Spitzer-Finds-Clarity-in-the-Inner-Milky-Way). Now, data from the very center of that picture are being presented at a different contrast to better highlight this jam-packed region. In visible-light pictures, it is all but impossible to see the heart of our galaxy, but infrared light penetrates the shroud of dust giving us this unprecedented view. In this Spitzer image, the myriad of stars crowding the center of our galaxy creates the blue haze that brightens towards the center of the image. The green features are from carbon-rich dust molecules, called polycyclic aromatic hydrocarbons, which are illuminated by the surrounding starlight as they swirl around the galaxy's core. The yellow-red patches are the thermal glow from warm dust. The polycyclic aromatic hydrocarbons and dust are associated with bustling hubs of young stars. These materials, mixed with gas, are required for making new stars. The brightest white feature at the center of the image is the central star cluster in our galaxy. At a distance of 26,000 light years away from Earth, it is so distant that, to Spitzer's view, most of the light from the thousands of individual stars is blurred into a single glowing blotch. Astronomers have determined that these stars are orbiting a massive black hole that lies at the very center of the galaxy. The region pictured here is immense, with a horizontal span of 2,400 light-years (5.3 degrees) and a vertical span of 1,360 light-years (3 degrees). Though most of the objects seen in this image are located near the galactic center, the features above and below the galactic plane tend to lie closer to Earth. The image is a three-color composite, showing infrared observation. *Image: NASA/JPL-Caltech \[[high-resolution](http://www.spitzer.caltech.edu/uploaded_files/images/0008/2893/sig11-003_Lrg.jpg)\]* *Caption: [NASA/JPL/Spitzer space telescope](http://www.spitzer.caltech.edu/images/3560-sig11-003-Stars-Gather-in-Downtown-Milky-Way)*
152jul-5-2012
Solar Fireworks --------------- This image, captured by the Solar Dynamics Observatory, shows the M5.3 class solar flare that peaked on July 4, 2012, at 5:55 AM EDT. The flare is shown in the 131 Angstrom wavelength, a wavelength that is particularly good for capturing the radiation emitted from flares. The wavelength is typically colorized in teal as shown here. *Image: NASA/SDO/AIA/Helioviewer \[[high-resolution](http://www.nasa.gov/images/content/665242main_solar_flare_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2300.html)*
153jul-3-2012
Herbig-Haro Rocket ------------------ Resembling a Fourth of July skyrocket, Herbig-Haro 110 is a geyser of hot gas from a newborn star that splashes up against and ricochets off the dense core of a cloud of molecular hydrogen. Although the plumes of gas look like whiffs of smoke, they are actually billions of times less dense than the smoke from a July 4 firework. This Hubble Space Telescope photo shows the integrated light from plumes, which are light-years across. Herbig-Haro (HH) objects come in a wide array of shapes, but the basic configuration stays the same. Twin jets of heated gas, ejected in opposite directions away from a forming star, stream through interstellar space. Astronomers suspect that these outflows are fueled by gas accreting onto a young star surrounded by a disk of dust and gas. The disk is the "fuel tank," the star is the gravitational engine, and the jets are the exhaust. When these energetic jets slam into colder gas, the collision plays out like a traffic jam on the interstate. Gas within the shock front slows to a crawl, but more gas continues to pile up as the jet keeps slamming into the shock from behind. Temperatures climb sharply, and this curving, flared region starts to glow. These "bow shocks" are so named because they resemble the waves that form at the front of a boat. In the case of the single HH 110 jet, astronomers observe a spectacular and unusual permutation on this basic model. Careful study has repeatedly failed to find the source star driving HH 110, and there may be good reason for this: perhaps the HH 110 outflow is itself generated by another jet. Astronomers now believe that the nearby HH 270 jet grazes an immovable obstacle — a much denser, colder cloud core — and gets diverted off at about a 60-degree angle. The jet goes dark and then reemerges, having reinvented itself as HH 110. The jet shows that these energetic flows are like the erratic outbursts from a Roman candle. As fast-moving blobs of gas catch up and collide with slower blobs, new shocks arise along the jet's interior. The light emitted from excited gas in these hot blue ridges marks the boundaries of these interior collisions. By measuring the current velocity and positions of different blobs and hot ridges along the chain within the jet, astronomers can effectively "rewind" the outflow, extrapolating the blobs back to the moment when they were emitted. This technique can be used to gain insight into the source star's history of mass accretion. *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/2012/30/image/a/format/xlarge_web/)\]* *Caption: [Hubble Heritage Team](http://hubblesite.org/newscenter/archive/releases/2012/30/image/a/)*
154jul-2-2012
Green Flames ------------ The Flame Nebula sits on the eastern hip of Orion the Hunter, a constellation most easily visible in the northern hemisphere during winter evenings. This view of the Flame nebula from WISE, NASA’s Wide-field Infrared Survey Explorer, shows an expanded view over one previously released of this enormous space cloud (http://wise.ssl.berkeley.edu/gallery\_FlameNebula.html). The previous image was made from data WISE collected after its coolant began to run out, when only three of WISE’s infrared bands were in operation. The flame nebula is a very infrared-bright region, and the reduced sensitivity during the 3-band phase of the WISE mission worked to the advantage of astronomers interested in studying the brightest parts of this region without so much glare. This new image includes more data collected from all of WISE’s four infrared bands. This view takes in a vast cloud of gas and dust where new stars are being born. Three familiar nebulae are visible in the central region: the Flame nebula, the Horsehead nebula, and NGC 2023. The Flame is the brightest and largest in the image. It is being lit up by a star inside it that is 20 times the mass of the sun and would be as bright to our eyes as the other stars in Orion’s belt if it weren’t for all the surrounding dust, which makes it appear 4 billion times dimmer than it really is. NGC 2023 is the bright knot below the Flame. The famous Horsehead nebula is visible poking out of the edge of the cloud, just to the right of NGC 2023 and down a touch. It takes on a very different view in infrared compared to visible light. In visible light, the horse’s head is a silhouetted dark cloud in front of glowing gas. But here, we see the dust in that dark cloud glowing in infrared light. Two of the three stars in Orion’s belt are visible in this image, but despite their prominence to our eyes in the night sky, they are somewhat unremarkable as seen by WISE. Alnitak, the far left star in Orion’s belt, is a multiple blue-giant star system located 736 light-years away. In this image, it is located just to the right of the central part of the Flame nebula. Alnilam, the middle star of Orion’s belt, is a variable blue supergiant, located 1,980 light-years away. Despite having a radius 24 times bigger than the sun, and luminosity 275,000 times greater than the sun, it only appears as a moderately bright star near the upper right corner of this image. Another noteworthy feature in this image is the bright red arc at the lower right. This arc surrounds the star sigma Orionis, the upper star in the sword of Orion, which hangs from his belt. It is a blue dwarf multiple star system, located 1,070 light-years away. It is moving through space at a breathtaking speed of 5,260,000 mph (2,400 kilometers per second). At that speed, winds from the star system crash into the gas and dust outside the system and create a bow shock, where material in front of the speeding Sigma Orionis system is piling up. The energy from the bow shock heats up dust in the region and makes it glow in infrared. Color in this image represents specific infrared wavelengths. Blue represents light emitted at 3.4-micron wavelengths, and cyan (blue-green) represents 4.6-microns, both of which come mainly from hot stars. Relatively cooler objects, such as the dust of the nebulae, appear green and red. Green represents 12-micron light and red represents 22-micron light. *Image: NASA/JPL-Caltech \[[high-resolution](http://www.nasa.gov/images/content/664737main_pia15635-full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/WISE/multimedia/pia15635.html)*
ESO155jun-29-2012
Cat's Paw --------- The Cat’s Paw Nebula (NGC 6334) is a vast region of star formation. This new portrait of NGC 6334 was created from images taken with the Wide Field Imager instrument at the 2.2-metre MPG/ESO telescope at the La Silla Observatory in Chile, combining images taken through blue, green and red filters, as well as a special filter designed to let through the light of glowing hydrogen. NGC 6334 lies about 5500 light-years from Earth in the constellation of Scorpius. The whole gas cloud is about 50 light-years across. NGC 6334 is one of the most active nurseries of massive stars in our galaxy and has been extensively studied by astronomers. The nebula conceals freshly minted brilliant blue stars — each nearly ten times the mass of our Sun and born in the last few million years. The region is also home to many baby stars that are buried deep in the dust, making them difficult to study. In total, the Cat’s Paw Nebula could contain several tens of thousands of stars. The nebula appears red because its blue and green light are scattered and absorbed more efficiently by material between the nebula and Earth. The red light comes predominantly from hydrogen gas glowing under the intense glare of hot young stars. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/eso1003a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso1003a/)*
Iztok Bončina/ESO156jun-28-2012
Starry Night Above La Silla --------------------------- The stars rotate around the southern celestial pole during a night at ESO’s La Silla Observatory in northern Chile. The fuzzy parts in the trails on the right are due to the Magellanic Clouds, two small galaxies neighbouring the Milky Way. The dome seen in the image hosts ESO’s 3.6-metre telescope and is home to HARPS (High Accuracy Radial velocity Planet Searcher), the world’s foremost exoplanet hunter. The rectangular building seen in the lower right of the image contains the 0.25-metre TAROT telescope, designed to react very quickly when a gamma-ray burst is detected. Other telescopes at La Silla include the 2.2-metre MPG/ESO telescope, and the 3.58-metre New Technology Telescope, the first telescope to use active optics and, as such, the precursor to all modern large telescopes. La Silla was ESO’s first observing site and is still one of the premier observatories in the southern hemisphere. *Image: Iztok Bončina/ESO \[[high-resolution](http://www.eso.org/public/archives/images/screen/potw1043a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/potw1043a/)*
157jun-27-2012
Blueberry Crater ---------------- This color image of an unnamed rayed crater shows bright rays radiating from the crater, which has a distinctly blue center. A number of rayed craters have been seen on Mercury, with the longest rays coming from Hokusai. The rays are usually observed from geologically young craters and vary in shape and size. This crater has rays extending up to 200km (124miles) away from the crater. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://www.nasa.gov/images/content/663201main_messenger_orbit_image20120627_1_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/messenger/multimedia/messenger_orbit_image20120627_1.html)*
158jun-26-2012
Icy Clouds ---------- In both the Earth's Northern and Southern Hemispheres polar mesospheric clouds are at the peak of their visibility, during their respective late spring and early summer seasons. Visible from aircraft in flight, the International Space Station and from the ground at twilight, the clouds typically appear as delicate, shining threads against the darkness of space--hence their other names of noctilucent or "night-shining" clouds. On June 13, 2012, when this image was taken from the space station as it passed over the Tibetan Plateau, polar mesospheric clouds were also visible to aircraft flying over Canada. In addition to the still image above, the station crew took a time-lapse image sequence of polar mesospheric clouds several days earlier on June 5, while passing over western Asia. It is first such sequence of images of the phenomena taken from orbit. Polar mesospheric clouds form between 47 to 53 miles (76 to 85 kilometers) above Earth’s surface when there is sufficient water vapor at these high altitudes to freeze into ice crystals. The clouds are illuminated by the sun when it is just below the visible horizon, lending them their night-shining properties. In addition to the polar mesospheric clouds trending across the center of the image, lower layers of the atmosphere are also illuminated. The lowest layer of the atmosphere visible in this image--the stratosphere--is indicated by dim orange and red tones near the horizon. *Image: NASA \[[high-resolution](http://www.nasa.gov/images/content/662919main_ISS031-E-116058_lrg_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2292.html)*
159jun-25-2012
Saturn Jet Stream ----------------- A particularly strong jet stream churns through Saturn's northern hemisphere in this false-color view from NASA's Cassini spacecraft. Clouds associated with the jet stream can be seen in the upper right about a third of the way down from the top of this image. The jet stream clouds appear like a thin, bright orange line here. Moving west and closer to the center of the image, the feature drops south. Farther to the west of this discontinuity, or drop, a blurrier form of the jet stream clouds continues to move along the latitude circle. The winds of Saturn's jet streams are zonal, meaning they move eastward or westward at particular latitudes. This jet stream is located at about 42 degrees north latitude, and has been visible on Saturn since the days of NASA’s Voyager spacecraft. In the Voyager days, this jet stream had an undulating appearance, leading scientists to dub it the "ribbon wave". The planet's atmosphere is always changing, and the jet stream now looks nothing like a ribbon. Saturn's atmosphere and its rings are shown here in a false color composite made from three images taken in near infrared light through filters that are sensitive to varying degrees of methane absorption. Red and orange colors in this view indicate clouds that are deep in the atmosphere. Yellow and green colors, most noticeable near the top of the view, indicate intermediate clouds. White and blue indicate high clouds and haze. The white clouds of the equatorial region appear oversaturated because the image was specially processed to bring out the wave. The rings, in the upper left and lower left of the image, appear bright blue because they are outside of the atmosphere and not affected by methane absorption. This view looks toward the northern, unilluminated side of the rings from about 36 degrees above the ring plane. The images were taken with the Cassini spacecraft wide-angle camera on Jan. 13, 2008 using a combination of spectral filters sensitive to wavelengths of near-infrared light. The image filtered at 890 nanometers is projected as blue. The image filtered at 728 nanometers is projected as green, and the image filtered at 752 nanometers is projected as red. The view was acquired at a distance of approximately 810,000 miles (1.3 million kilometers) from Saturn and at a sun-Saturn-spacecraft, or phase, angle of 55 degrees. Image scale is 46 miles (74 kilometers) per pixel. *Image: NASA/JPL-Caltech/SSI \[[high-resolution](http://www.nasa.gov/images/content/662437main_pia14916-43_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/cassini/multimedia/pia14916.html)*
ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray)160jun-22-2012
Lobes of Centaurus A -------------------- Colour composite image of Centaurus A, revealing the lobes and jets emanating from the active galaxy’s central black hole. This is a composite of images obtained with three instruments, operating at very different wavelengths. The 870-micron submillimetre data, from LABOCA on APEX, are shown in orange. X-ray data from the Chandra X-ray Observatory are shown in blue. Visible light data from the Wide Field Imager (WFI) on the MPG/ESO 2.2 m telescope located at La Silla, Chile, show the stars and the galaxy’s characteristic dust lane in close to "true colour". *Image: ESO/WFI (Optical); MPIfR/ESO/APEX/A.Weiss et al. (Submillimetre); NASA/CXC/CfA/R.Kraft et al. (X-ray) \[[high-resolution](http://www.eso.org/public/archives/images/large/eso0903a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0903a/)*
161jun-21-2012
Big-Bird-Shaped Coronal Hole on the Sun --------------------------------------- This image of a coronal hole on the sun bears a remarkable resemblance to the 'Sesame Street' character Big Bird. Coronal holes are regions where the sun's corona is dark. These features were discovered when X-ray telescopes were first flown above the Earth's atmosphere to reveal the structure of the corona across the solar disc. Coronal holes are associated with 'open' magnetic field lines and are often found at the sun’s poles. The high-speed solar wind is known to originate in coronal holes. The solar wind escaping from this hole reached Earth around June 5-7, 2012. *Image: NASA/AIA \[[high-resolution](http://www.nasa.gov/images/content/656133main_coronalhole_sdo_blank_full.jpg)\]* *Caption: [NASA/AIA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2268.html)*
162jun-20-2012
War and Peace Nebula -------------------- ESO’s Very Large Telescope (VLT) has taken the most detailed image so far of a spectacular part of the stellar nursery called NGC 6357. The view shows many hot young stars, glowing clouds of gas and weird dust formations sculpted by ultraviolet radiation and stellar winds. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/large/eso1226a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso1226a/)*
163jun-19-2012
Beautiful Arctic ---------------- Fifteen orbits of the recently launched Suomi NPP satellite provided the VIIRS instrument enough time (and longitude) to gather the pixels for this synthesized view of Earth showing the Arctic, Europe, and Asia. Suomi NPP orbits the Earth about 14 times each day and observes nearly the entire surface. The NPP satellite continues key data records that are critical for climate change science. *Image: NASA/GSFC \[[high-resolution](http://www.nasa.gov/images/content/660720main_blue_marble_arctic_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2286b.html)*
164jun-18-2012
Dark Side of Titan ------------------ The Cassini spacecraft looks toward the dark side of Saturn's largest moon and captures the halo-like ring produced by sunlight scattering through the periphery of Titan's atmosphere. A detached, high-altitude global haze layer encircles Titan. See Titan's Halo to learn more. This view looks toward the Saturn-facing side of Titan (3,200 miles, or 5,150 kilometers across). North on Titan is up and rotated 29 degrees to the left. The image was taken in visible green light with the Cassini spacecraft wide-angle camera on Jan. 30, 2012. The view was obtained at a distance of approximately 123,000 miles (197,000 kilometers) from Titan and at a Sun-Titan-spacecraft, or phase, angle of 162 degrees. Image scale is 7 miles (12 kilometers) per pixel. *Image: NASA/JPL-Caltech/Space Science Institute \[[high-resolution](http://photojournal.jpl.nasa.gov/jpeg/PIA14613.jpg)\]* *Caption: [Casinni Solstice Team](http://saturn.jpl.nasa.gov/photos/imagedetails/index.cfm?imageId=4540)*
165jun-15-2012
Out of Sync ----------- New results based on the two objects shown here are challenging the prevailing ideas as to how supermassive black holes grow in the centers of galaxies. NGC 4342 and NGC 4291, the two galaxies in the study, are nearby in cosmic terms at distances of 75 million and 85 million light years respectively. In these composite images, X-rays from NASA's Chandra X-ray Observatory are colored blue, while infrared data from the 2MASS project are seen in red. Astronomers had known from previous observations that these galaxies host black holes with unusually large masses compared to the mass contained in the central bulge of stars. To study the dark matter envelopes contained in each galaxy, Chandra was used to examine their hot gas content, which was found to be widespread in both objects. By analyzing the distribution of the hot gas, researchers were able to test whether the galaxies had "lost weight" through stars being pulled away during a tidal encounter with another galaxy. Estimates of the pressure of the hot gas, which must balance the gravitational pull of all the matter in the galaxy, showed that massive envelopes of dark matter must exist around each galaxy. Since this tidal stripping would have severely depleted the dark matter, which is more loosely tied to the galaxies than the stars, this process is unlikely to have occurred in either galaxy. The new results using NGC 4342 and NGC 4291 challenge the long-held idea that black holes at the centers of galaxies always grow in tandem with the bulges of stars that surround them. Rather this study suggests that the two supermassive black holes and their evolution are tied more closely to the amount and distribution of dark matter in each galaxy. In this picture the weights of the black hole and the dark matter envelope in these two galaxies are "normal" and the galaxies are underweight because they formed unusually slowly. *Image: X-ray: NASA/CXC/SAO/A.Bogdan et al; Infrared: 2MASS/UMass/IPAC-Caltech/NASA/NSF \[[high-resolution](http://chandra.harvard.edu/photo/2012/ngc4342/ngc4342.jpg)\]* *Caption: [Chandra](http://chandra.harvard.edu/photo/2012/ngc4342/)*
166jun-14-2012
Blue Red Planet --------------- This image shows layered bedrock composed of light- and intermediate-toned materials on Mars. There are also darker bed forms that fill in low-lying topography, such as impact craters. In the center of the image is a valley with darker fill extending from left to right. The darker materials within the valley might be fluvial sediments. At HiRISE resolution, we might be able to decipher the properties of the bedrock as well as what deposited the sediments. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2560/ESP_026359_1990.jpg)\]* *Caption: [HiRISE Science Team](http://hirise.lpl.arizona.edu/ESP_026359_1990)*
167jun-13-2012
Galactic Center --------------- This sweeping panorama is the sharpest infrared picture ever made of the Milky Way's galactic core, where massive stars are forming. *Image: Credit for Hubble image: NASA, ESA, and Q.D. Wang (University of Massachusetts, Amherst) Credit for Spitzer image: NASA, Jet Propulsion Laboratory, and S. Stolovy (Spitzer Science Center/Caltech) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2009-02-a-print.jpg)\]* *Caption: [NASA](http://hubblesite.org/gallery/album/the_universe/pr2009002a/)*
168jun-12-2012
The Veil Nebula --------------- The Veil Nebula, left behind by the explosion of a massive star thousands of years ago, is one of the largest and most spectacular supernova remnants in the sky. The image was taken with Hubble's Wide Field Planetary Camera 2 in November 1994 and August 1997. *Image: NASA, ESA, and the Hubble Heritage (STScI/AURA)-ESA/Hubble Collaboration; Acknowledgment: J. Hester (Arizona State University) \[[high-resolution](http://www.nasa.gov/images/content/659202main_veil_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2280.html)*
ESO169jun-11-2012
Christmas Tree Cluster ---------------------- This colour image of the region known as NGC 2264 — an area of sky that includes the sparkling blue baubles of the Christmas Tree star cluster and the Cone Nebula — was created from data taken through four different filters (B, V, R and H-alpha) with the Wide Field Imager at ESO's La Silla Observatory, 2400 m high in the Atacama Desert of Chile in the foothills of the Andes. The image shows a region of space about 30 light-years across. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/publicationjpg/eso0848a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso0848a/)*
170jun-8-2012
High Pressure Hole ------------------ High-pressure weather systems often bring fair weather and relatively clear skies. In early June 2012, a high off the coast of Tasmania did just that...and in spectacular fashion. The Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA’s Aqua satellite acquired this view of a hole in a cloud formation at 3:00 p.m. local time (05:00 Universal Time) on June 5, 2012. The weather system over the Great Australian Bight cut out the oval-shaped hole from a blanket of marine stratocumulus clouds. The cloud hole, with a diameter that stretched as far as 1,000 kilometers (620 miles) across, was caused by sinking air associated with an area of high pressure near the surface. Globally, the average sea-level pressure is about 1013 millibars; at the center of this high, pressures topped 1,040 millibars. Sea-level pressure maps published by the Australian Bureau of Meteorology on June 5 showed that the shape of the cloud hole matched the shape of the high-pressure area. However, the center of high pressure and the cloud hole didn't match precisely; the center of the high was near the western edge of the clear area, about 100 kilometers from the cloud edge. In general, winds blow outward and away from areas of high pressure. As a result, areas of high pressure pull air downward. As the air sinks, it also warms, increasing the rate of evaporation and making it difficult for the air to sustain clouds. Areas of low pressure, by contrast, pull air upward and generate clouds and stormy weather. While low-pressure systems often produce circular cyclonic storms and clouds, high-pressure systems (which are sometimes called anticyclones) can yield large circular areas of clear skies. “You could call it an anti-storm,” quipped NASA Langley atmospheric scientist Patrick Minnis. According to NASA Goddard atmospheric scientists Joanna Joiner and Arlindo da Silva, weather models predicted the cloud formation nearly perfectly. “We checked the Global Modeling and Assimilation Office (GMAO) forecast, and it really nailed the system,” Joiner said. *Image: Jeff Schmaltz, LANCE MODIS Rapid Response \[[high-resolution](http://eoimages.gsfc.nasa.gov/images/imagerecords/78000/78208/SouthIndianOcean_amo_2012157_lrg.jpg)\]* *Caption: [Adam Voiland with information from Patrick Minnis, NASA Langley; Joanna Joiner, NASA Goddard; Steve Lang; NASA Goddard; and Heather Hyre, NASA Goddard](http://earthobservatory.nasa.gov/IOTD/view.php?id=78208)*
171jun-7-2012
Mars' Climate Change -------------------- ESA’s Mars Express has provided images of a remarkable crater on Mars that may show evidence that the planet underwent significant periodic fluctuations in its climate due to changes in its rotation axis. On 19 June 2011, Mars Express pointed its high-resolution stereo camera at the Arabia Terra region of Mars, imaging the Danielson and Kalocsa craters. Danielson crater is named after the late George E Danielson, who was instrumental in the development of many spacecraft cameras flown to Mars. Seen to the right (north) in the image, it is the larger crater, roughly 60 km across. Kalocsa crater lies in the centre of the image and is smaller, about 33 km in diameter and a kilometre shallower than Danielson. It is named after a town in Hungary famed for its astronomical observatory. Danielson crater, like many in the Arabia Terra region, is filled with layered sediments, which in this instance have been heavily eroded over time. Within the crater are peculiarly layered buttes, known as yardangs. Yardangs are streamlined hills carved from bedrock or any consolidated or semi-consolidated material by abrasive dust and sand particles carried in the wind. They are seen on Earth in desert regions, with notable examples in North Africa, Central Asia and Arizona in the United States. In the case of Danielson crater, it is believed that sediments were cemented by water, possibly from an ancient deep groundwater reservoir, before being eroded by the wind. The orientation of the yardangs leads scientists to theorise that strong north–northeasterly winds (from the lower right in the image) both deposited the original sediments and then caused their subsequent erosion in a later drier period of martian history. A 30 km-long field of darker dunes can be seen bisecting the yardangs and is thought to have formed at a later epoch. The crater floor of Danielson shows evidence for a series of alternating sedimentary layers with roughly uniform thickness and separation. Some scientists believe that this indicates periodic fluctuations in the climate of Mars, triggered by regular changes in the planet’s axis of rotation. The different layers would have been laid down during different epochs. By marked contrast, Kalocsa crater shows a completely different topography. Here, no layered sediments are seen. This is thought to be due to the higher altitude of its floor, with the crater not tapping in to the suspected underlying ancient water reservoir. Another hypothesis is that this crater is younger than its neighbour, created when water was not present anymore. *Image: ESA/DLR/FU Berlin (G. Neukum) \[[high-resolution](http://esamultimedia.esa.int/images/marsexpress/555-20120514-10468-co-DanielsonCrater_H1.jpg)\]* *Caption: [ESA](http://www.esa.int/export/esaSC/SEMD285XX2H_index_0.html)*
172jun-6-2012
Necklace Nebula --------------- A giant cosmic necklace glows brightly in this NASA Hubble Space Telescope image. The object, aptly named the Necklace Nebula, is a recently discovered planetary nebula, the glowing remains of an ordinary, Sun-like star. The nebula consists of a bright ring, measuring 12 trillion miles across, dotted with dense, bright knots of gas that resemble diamonds in a necklace. The knots glow brightly due to absorption of ultraviolet light from the central stars. A pair of stars orbiting very close together produced the nebula, also called PN G054.2-03.4. About 10,000 years ago one of the aging stars ballooned to the point where it enveloped its companion star. This caused the larger star to spin so fast that much of its gaseous envelope expanded into space. Due to centrifugal force, most of the gas escaped along the star's equator, producing a dense ring. The embedded bright knots are the densest gas clumps in the ring. The stars are furiously whirling around each other, completing an orbit in a little more than a day. (For comparison, Mercury, the closest planet to the Sun, takes 88 days to orbit the Sun.) The Necklace Nebula is located 15,000 light-years away in the constellation Sagitta (the Arrow). In this composite image, taken on July 2, 2011, Hubble's Wide Field Camera 3 captured the glow of hydrogen (blue), oxygen (green), and nitrogen (red). *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://hubblesite.org/newscenter/archive/releases/2011/24/image/a/format/xlarge_web/)\]* *Caption: [NASA](http://hubblesite.org/newscenter/archive/releases/2011/24/image/a/)*
173jun-5-2012
Arc of Venus ------------ When Venus transits the sun on June 5th and 6th, an armada of spacecraft and ground-based telescopes will be on the lookout for something elusive and, until recently, unexpected: The Arc of Venus. "I was flabbergasted when I first saw it during the 2004 transit," recalls astronomy professor Jay Pasachoff of Williams College. "A bright, glowing rim appeared around the edge of Venus soon after it began to move into the sun." For a brief instant, the planet had turned into a "ring of fire." Researchers now understand what happened. Backlit by the sun, Venus's atmosphere refracted sunlight passing through layers of air above the planet's cloudtops, creating an arc of light that was visible in backyard telescopes and spacecraft alike. It turns out, researchers can learn a lot about Venus by observing the arc. Indeed, it touches on some of the deepest mysteries of the second planet. "We do not understand why our sister planet's atmosphere evolved to be so different than Earth's," explains planetary scientist Thomas Widemann of the Observatoire de Paris. Earth and Venus are similar distances from the sun, are made of the same basic materials, and are almost perfect twins in terms of size. Yet the two planets are wrapped in stunningly dissimilar blankets of air. Venus's atmosphere is almost 100 times more massive than Earth's and consists mainly of CO2, a greenhouse gas that raises the surface temperature to almost 900°F. Clouds of sulfuric acid tower 14 miles high and whip around the planet as fast as 220 mph. A human being transported to this hellish environment would be crushed, suffocate, desiccate, and possibly ignite. For the most part, planetary scientists have no idea how Venus turned out this way. "Our models and tools cannot fully explain Venus, which means we lack the tools for understanding our own planet," points out Widemann. "Caring about Venus is caring about ourselves." One of the biggest mysteries of Venus is super-rotation. The whole atmosphere circles the planet in just four Earth days, much faster than the planet's spin period of 243 days. "The dynamics of super-rotation are still a puzzle despite a wealth of data from landmark missions such as NASA's Pioneer Venus, Russia's Venera and VEGA missions, NASA's Magellan and more recently ESA's Venus Express." This is where the Arc of Venus comes in. The brightness of the arc reveals the temperature and density structure of Venus's middle atmosphere, or "mesosphere," where the sunlight is refracted. According to some models, the mesosphere is key to the physics of super-rotation. By analyzing the lightcurve of the arc, researchers can figure out the temperature and density of this critical layer from pole to pole. When the arc appeared in 2004, the apparition took astronomers by surprise; as a result, their observations were not optimized to capture and analyze the fast-changing ring of light. This time, however, they are ready. Together, Pasachoff and Widemann have organized a worldwide effort to monitor the phenomenon on June 5th, 2012. "We're going to observe the arc using 9 coronagraphs spaced around the world," says Pasachoff. "Observing sites include Haleakala, Big Bear, and Sacramento Peak. Japan's Hinode spacecraft and NASA's Solar Dynamics Observatory will also be gathering data." Pasachoff has some advice for amateur astronomers who wish to observe the arc. "The best times to look are ingress and egress--that is, when the disk of Venus is entering and exiting the sun. Ingress is between 22:09 and 22:27 UT on June 5th; egress occurs between 04:32 and 04:50 UT. Be sure your telescope is safely filtered. Both white light and H-alpha filters might possibly show the arc." *Image: André Rondi \[[high-resolution](http://www.astrosurf.com/rondi/venus2004/)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/sunearth/news/venus-arc.html)*
174jun-4-2012
Bubbles in Carina ----------------- The Carina Nebula, by ESA’s Herschel space observatory. The image shows the effects of massive star formation – powerful stellar winds and radiation have carved pillars and bubbles in dense clouds of gas and dust. The image covers approximately 2.3 x 2.3 degrees of the Carina Nebula complex and was mapped using Herschel instruments PACS and SPIRE at wavelengths of 70, 160, and 250 microns, corresponding to the blue, green, and red channels, respectively. North is to the upper left and east is to the lower left. *Image: ESA/PACS/SPIRE/Thomas Preibisch, Universitäts-Sternwarte München, Ludwig-Maximilians-Universität München, Germany \[[high-resolution](http://www.esa.int/images/Carina_B70_G160_R250_10052012_BIS_Comp_H.jpg)\]* *Caption: [ESA](http://www.esa.int/esaSC/SEM0DE2XN2H_index_1.html)*
175jun-1-2012
Colorful Asteroid History ------------------------- As ESA's Rosetta spacecraft flew past the main-belt asteroid (21) Lutetia, the OSIRIS camera on Rosetta surveyed the part of Lutetia that was visible during this period – about half of its entire surface, mostly coinciding with the asteroid's northern hemisphere. The asteroid's North Pole is indicated with a black dot. The unique, close-up images obtained by OSIRIS have allowed scientists to identify regions characterised by very distinct geological properties with an accuracy of a few hundred metres. By tracing craters and other features on Lutetia's surface, scientists have put together a geological map for the asteroid. Their studies have shown that Lutetia's surface comprises regions spanning a wide range of ages: each of them reveals a chapter in the long and tumultuous history of this asteroid. The most ancient portions on the surface of Lutetia are the heavily cratered Achaia and Noricum regions, shown in red and yellow in the upper and lower part of the image, respectively. With ages between 3.4 and 3.7 billion years or more, these two regions are almost as old as the asteroid itself. Massilia, the largest crater identified on the asteroid, is located in a younger region named Narbonensis. This region is shown in blue on the right side of the image: the depression due to the large crater is clearly visible. With a diameter of 57 km, Massilia provides evidence of the most dramatic event in the history of Lutetia. The youngest patch on the surface of Lutetia is the Baetica region, located in the vicinity of the asteroid's North Pole and shown in green at the centre of the image. This region hosts a number of superimposed craters, named the North Polar Crater Cluster (NPCC), which include three large ones with sizes exceeding 10 km. These craters represent the signature left by a series of subsequent impacts that took place quite recently on geological timescales – namely, in the last few hundred million years. *Image: Thomas et al., (adapted from Massironi et al.,) Planetary and Space Science, Vol.66, 2012 \[[high-resolution](http://sci.esa.int/science-e-media/img/dc/Rosetta_Lutetia_surface-regions.jpg)\]* *Caption: [ESA](http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=50396)*
176may-31-2012
The Mouth of Morava Valles on Mars ---------------------------------- Morava Valles drained Ladon Basin and discharged towards the large regions of chaotic terrain near the head of Ares Valles. Because the valley emerges full bore from Ladon Basin (much like the Niagara river emerges from Lake Erie on the Earth), it has been hypothesized that it was formed when a lake overflowed the basin. There are numerous valleys, including the large Ladon Valles, that end along the margin of Ladon Basin. Some of the outcrops visible in this image and elsewhere in the basin show evidence of layering due to deposition of sediments. Comparison of the nature and extent of layers exposed here and elsewhere around Ladon basin should help to constrain their origin, by water flow or other processes. *Image: NASA/JPL/University of Arizona \[[high-resolution](http://hirise.lpl.arizona.edu/images/wallpaper/2560/ESP_026007_1640.jpg)\]* *Caption: [John Grant](http://hirise.lpl.arizona.edu/ESP_026007_1640)*
177may-30-2012-2
Neptune ------- During August 16 and 17, 1989, the Voyager 2 narrow-angle camera was used to photograph Neptune almost continuously, recording approximately two and one-half rotations of the planet. These images represent the most complete set of full disk Neptune images that the spacecraft will acquire. This picture from the sequence shows two of the four cloud features which have been tracked by the Voyager cameras during the past two months. The large dark oval near the western limb (the left edge) is at a latitude of 22 degrees south and circuits Neptune every 18.3 hours. The bright clouds immediately to the south and east of this oval are seen to substantially change their appearances in periods as short as four hours. The second dark spot, at 54 degrees south latitude near the terminator (lower right edge), circuits Neptune every 16.1 hours. This image has been processed to enhance the visibility of small features, at some sacrifice of color fidelity. The Voyager Mission is conducted by JPL for NASA's Office of Space Science and Applications. *Image: NASA/JPL \[[high-resolution](photojournal.jpl.nasa.gov/jpeg/PIA00046.jpg)\]* *Caption: [NASA](http://photojournal.jpl.nasa.gov/catalog/PIA00046)*
178may-29-2012
Crater Menagerie on Mercury --------------------------- This color image features six named craters. The crater at the very top of the scene displaying bright crater floor material, terraced walls, and central peaks, is Tyagaraja, which has a diameter of 97 km. The large crater in the center of the image, also featuring some bright crater floor material, terraced walls, and central peaks, as well as clear crater chains, is Zeami. The large crater south of Zeami with a smaller crater in its lower half is Sophocles, which has a diameter of 142 km. To the right of Sophocles there is a smaller crater (diameter of 46 km) that appears fresher, and in this image, has orange tinted material surrounding its crater rim; this is Theophanes. To the left of Sophocles there is a similarly sized crater named Goya. Finally, near the upper right quadrant of the image is the newly named Stevenson crater, with the distinctive "X" shape formed by crossing chains of secondary craters. *Image: NASA/Johns Hopkins University Applied Physics Laboratory/Carnegie Institution of Washington \[[high-resolution](http://messenger.jhuapl.edu/gallery/sciencePhotos/pics/EW0242837980G.3band.mapped.png)\]* *Caption: [Mercury Messenger Team](http://messenger.jhuapl.edu/gallery/sciencePhotos/image.php?gallery_id=2&image_id=859)*
179may-24-2012
Coma Cluster Galaxy ------------------- A long-exposure Hubble Space Telescope image shows a majestic face-on spiral galaxy located deep within the Coma Cluster of galaxies, which lies 320 million light-years away in the northern constellation Coma Berenices. The galaxy, known as NGC 4911, contains rich lanes of dust and gas near its center. These are silhouetted against glowing newborn star clusters and iridescent pink clouds of hydrogen, the existence of which indicates ongoing star formation. Hubble has also captured the outer spiral arms of NGC 4911, along with thousands of other galaxies of varying sizes. The high resolution of Hubble's cameras, paired with considerably long exposures, made it possible to observe these faint details. NGC 4911 and other spirals near the center of the cluster are being transformed by the gravitational tug of their neighbors. In the case of NGC 4911, wispy arcs of the galaxy's outer spiral arms are being pulled and distorted by forces from a companion galaxy (NGC 4911A), to the upper right. The resultant stripped material will eventually be dispersed throughout the core of the Coma Cluster, where it will fuel the intergalactic populations of stars and star clusters. The Coma Cluster is home to almost 1,000 galaxies, making it one of the densest collections of galaxies in the nearby universe. It continues to transform galaxies at the present epoch, due to the interactions of close-proximity galaxy systems within the dense cluster. Vigorous star formation is triggered in such collisions. Galaxies in this cluster are so densely packed that they undergo frequent interactions and collisions. When galaxies of nearly equal masses merge, they form elliptical galaxies. Merging is more likely to occur in the center of the cluster where the density of galaxies is higher, giving rise to more elliptical galaxies. This natural-color Hubble image, which combines data obtained in 2006, 2007, and 2009 from the Wide Field Planetary Camera 2 and the Advanced Camera for Surveys, required 28 hours of exposure time. *Image: NASA, ESA, and the Hubble Heritage Team (STScI/AURA) \[[high-resolution](http://imgsrc.hubblesite.org/hu/db/images/hs-2010-24-a-xlarge_web.jpg)\]* *Caption: [NASA](http://hubblesite.org/newscenter/archive/releases/2010/24/image/a/)*
180may-23-2012
Martian Landscape ----------------- NASA's Mars Rover Opportunity catches its own late-afternoon shadow in this dramatically lit view eastward across Endeavour Crater on Mars. The rover used the panoramic camera (Pancam) between about 4:30 and 5:00 p.m. local Mars time to record images taken through different filters and combined into this mosaic view. Most of the component images were recorded during the 2,888th Martian day, or sol, of Opportunity's work on Mars (March 9, 2012). At that time, Opportunity was spending low-solar-energy weeks of the Martian winter at the Greeley Haven outcrop on the Cape York segment of Endeavour's western rim. In order to give the mosaic a rectangular aspect, some small parts of the edges of the mosaic and sky were filled in with parts of an image acquired earlier as part of a 360-degree panorama from the same location. Opportunity has been studying the western rim of Endeavour Crater since arriving there in August 2011. This crater spans 14 miles (22 kilometers) in diameter, or about the same area as the city of Seattle. This is more than 20 times wider than Victoria Crater, the largest impact crater that Opportunity had previously examined. The interior basin of Endeavour is in the upper half of this view. The mosaic combines about a dozen images taken through Pancam filters centered on wavelengths of 753 nanometers (near infrared), 535 nanometers (green) and 432 nanometers (violet). The view is presented in false color to make some differences between materials easier to see, such as the dark sandy ripples and dunes on the crater's distant floor. *Image: NASA/JPL-Caltech/Cornell/Arizona State Univ. \[[high-resolution](http://www.nasa.gov/images/content/652371main_mars_iotd_full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2255.html)*
181may-22-2012
Strange Galaxy -------------- The peculiar galaxy Centaurus A (NGC 5128) is pictured in this image taken with by the Wide Field Imager attached to the MPG/ESO 2.2-metre telescope at the La Silla Observatory in Chile. With a total exposure time of more than 50 hours this is probably the deepest view of this peculiar and spectacular object every created. *Image: ESO \[[high-resolution](http://www.eso.org/public/archives/images/publicationjpg/eso1221a.jpg)\]* *Caption: [ESO](http://www.eso.org/public/images/eso1221a/)*
182may-21-2012
Tiny Methone ------------ NASA's Cassini spacecraft made its closest approach to Saturn's tiny moon Methone as part of a trajectory that will take it on a close flyby of another of Saturn's moons, Titan. The Titan flyby will put the spacecraft in an orbit around Saturn that is inclined, or tilted, relative to the plane of the planet's equator. The flyby of Methone took place on May 20 at a distance of about 1,200 miles (1,900 kilometers). It was Cassini's closest flyby of the 2-mile-wide (3-kilometer-wide) moon. The best previous Cassini images were taken on June 8, 2005, at a distance of about 140,000 miles (225,000 kilometers), and they barely resolved this object. Also on May 20, Cassini obtained images of Tethys, a larger Saturnian moon that is 660 miles (1,062 kilometers) across. The spacecraft flew by Tethys at a distance of about 34,000 miles (54,000 kilometers). Cassini's encounter with Titan, Saturn's largest moon, on May 22, is the first of a sequence of flybys that will put the spacecraft into an inclined orbit. At closest approach, Cassini will fly within about 593 miles (955 kilometers) of the surface of the hazy Titan. The flyby will angle Cassini's path around Saturn by about 16 degrees out of the equatorial plane, which is the same plane in which Saturn's rings and most of its moons reside. Cassini's onboard thrusters don't have the capability to place the spacecraft into orbits so inclined. But mission designers have planned trajectories that take advantage of the gravitational force exerted by Titan to boost Cassini into inclined orbits. Over the next few months, Cassini will use several flybys of Titan to change the angle of its inclination, building one on top of the other until Cassini is orbiting Saturn at around 62 degrees relative to the equatorial plane in 2013. Cassini hasn't flown in orbits this inclined since 2008, when it orbited at an angle of 74 degrees. This set of inclined orbits is expected to provide spectacular views of the rings and poles of Saturn. Further studies of Saturn's other moons will have to wait until around 2015, when Cassini returns to an equatorial orbit. "Getting Cassini into these inclined orbits is going to require the same level of navigation accuracy that the team has delivered in the past, because each of these Titan flybys has to stay right on the money," said Robert Mitchell, Cassini program manager at NASA's Jet Propulsion Laboratory, Pasadena, Calif. "However, with nearly eight years of experience to rely on, there's no doubt about their ability to pull this off." Cassini discovered Methone and two other small moons, Pallene and Anthe, between the orbits of Mimas and Enceladus between 2004 and 2007. The three tiny moons, called the Alkyonides group, are embedded in Saturn's E ring, and their surfaces are sprayed by ice particles originating from the jets of water ice, water vapor and organic compounds emanating from the south polar area of Enceladus. *Image: NASA/JPL-Caltech/SSI \[[high-resolution](http://saturn.jpl.nasa.gov/multimedia/images/raw/casJPGFullS73/N00189072.jpg)\]* *Caption: [NASA](http://www.jpl.nasa.gov/news/news.cfm?release=2012-140&rn=news.xml&rst=3373)*
183may-18-2012
Eclipse from Space ------------------ The joint JAXA/NASA Hinode satellite captured this image of a solar eclipse on Jan 6, 2011. The mission is set to observe the upcoming annular solar eclipse on May 20, 2012. Scientists often use an eclipse to help calibrate the instruments on the telescope by focusing in on the edge of the moon as it crosses the sun and measuring how sharp it appears in the images. An added bonus: Hinode's X-ray Telescope will be able to provide images of the peaks and valleys of the lunar surface. *Image: Hinode \[[high-resolution](http://www.nasa.gov/images/content/650665main_hinode-eclipse-orig_full.jpg)\]* *Caption: [Wired Science](http://www.nasa.gov/mission_pages/sunearth/news/eclipse-2012.html)*
184may-17-2012
Starburst Filament ------------------ The Herschel Space Observatory has discovered a giant, galaxy-packed filament ablaze with billions of new stars. The filament connects two clusters of galaxies that, along with a third cluster, will smash together in several billion years and give rise to one of the largest galaxy superclusters in the universe. The three galaxy clusters of the emerging supercluster, known as RCS2319, are seen in visible and X-ray light (purple) to the left. Observations by Herschel in infrared light appear to the right, with colored regions indicating greater infrared emissions. A white circle broadly outlines the 8 million light-year-long intergalactic filament in each image. In visible light, the filament does not stand out because dust obscures the star-formation activity in distant galaxies. Telescopes like Herschel, however, can detect the infrared glow of this dust as it is heated by newborn stars. The amount of infrared light suggests that the galaxies in the filament are cranking out the equivalent of about 1,000 new Suns in terms of mass per year. For comparison's sake, our Milky Way galaxy is producing about one Sun's mass-worth of new stars per year. Notably, the third galaxy cluster is off the edge of the image on the right. The reason behind this apparent snub is that the original research proposal called for making a map centered on the top cluster. During the observing run, astronomers did not know the filament existed, so its eventual discovery serves as a nice example of scientific serendipity. The team is now aiming to perform further follow-up observations to examine the filament in more detail. *Image: ESA/NASA/JPL-Caltech/CXC/McGill Univ. \[[high-resolution](http://www.nasa.gov/images/content/650741main_pia15659-full_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/mission_pages/herschel/multimedia/pia15659.html)*
Gemini Observatory/AURA185may-16-2012
Planetary Nebula ---------------- A new Legacy Image from the Gemini Observatory reveals the remarkable complexity of the planetary nebula Sharpless 2-71 (Sh 2-71). Embroiled in a bit of controversy over its “birth parents” the nebula likely resulted from interactions between a pair of two old and dying stars. Legacy images like this one share the stunning beauty of the universe as revealed by the twin 8-meter Gemini telescopes in Hawai‘i and Chile. *Image: Gemini Observatory/AURA \[[high-resolution](http://www.gemini.edu/images/pio/20120511sh2-71.jpg)\]* *Caption: [Gemini Observatory](http://www.gemini.edu/node/11815)*
186may-15-2012
It's Full of Stars ------------------ This is a composite of a series of images photographed from a mounted camera on the Earth-orbiting International Space Station, from approximately 240 miles above Earth. Space station hardware in the foreground includes the Mini-Research Module (MRM1, center) and a Russian Progress vehicle docked to the Pirs Docking Compartment (right). Expedition 31 Flight Engineer Don Pettit relayed some information about photographic techniques used to achieve the images: "My star trail images are made by taking a time exposure of about 10 to 15 minutes. However, with modern digital cameras, 30 seconds is about the longest exposure possible, due to electronic detector noise effectively snowing out the image. To achieve the longer exposures I do what many amateur astronomers do. I take multiple 30-second exposures, then 'stack' them using imaging software, thus producing the longer exposure." A total of 47 images photographed by the astronaut-monitored stationary camera were combined to create this composite. . *Image: NASA/Don Pettit \[[high-resolution](http://spaceflight.nasa.gov/gallery/images/station/crew-30/hires/jsc2012e051507_alt.jpg)\]* *Caption: [NASA](http://spaceflight.nasa.gov/gallery/images/station/crew-30/html/jsc2012e051507_alt.html)*
187may-14-2012
Cygnus Swirls ------------- Best known as a swan winging its way across the night, the constellation Cygnus is easily seen in the northern hemisphere's summertime sky. This new view of the Cygnus-X star-forming region by the Herschel Telescope highlights chaotic networks of dust and gas that point to sites of massive star formation. This image combines far-infrared data acquired at 70 micron (corresponding to the blue channel); 160 micron (corresponding to the green channel); and 250 micron (corresponding to the red channel). The observations were made on May 24, 2010, and Dec. 18, 2010. Herschel is a European Space Agency cornerstone mission, with science instruments provided by consortia of European institutes and with important participation by NASA. *Image: ESA/PACS/SPIRE/Martin Hennemann & Frederique Motte, Laboratoire AIM Paris-Saclay, CEA/Irfu -- CNRS/INSU -- Univ. Paris Diderot, France \[[high-resolution](http://www.nasa.gov/images/content/649274main_PIA15626_full.jpg)\]* *Caption: [NASA](http://www.nasa.gov/multimedia/imagegallery/image_feature_2248.html)*
