WIRED Staff
Science

Slideshow: Don't Set Your Watch by Saturn

How long is a day on Saturn? Scientists say they're no longer sure. Radio emissions recorded by the Cassini space probe hint that the period varies significantly. It's the second major discovery by the craft. Amit Asaravala reports from Pasadena, California.
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In this image, dark regions represent areas where Cassini is seeing into deeper levels in Saturn's atmosphere. The dark regions are relatively free of high clouds, and the light at these particular near-infrared wavelengths (centered at 727 nanometers) penetrates into the gaseous cloud-free atmosphere and is absorbed by methane. The image was taken with the Cassini spacecraft narrow-angle camera on May 15, 2004, from a distance of 24.7 million kilometers (15.4 million miles) from Saturn.Courtesy of NASA/JPL/Space Science Institute

See related story: Don't Set Your Watch by Saturn

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Saturn's peaceful beauty invites the Cassini spacecraft for a closer look in this natural-color view, taken during the spacecraft's approach to the planet. By this point in the approach sequence, Saturn was large enough that two narrow-angle camera images were required to capture an end-to-end view of the planet, its delicate rings and several of its icy moons. This image is a composite made from the two images.

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The Cassini spacecraft has beamed back a new, more detailed image of "smog"-enshrouded Titan. This view represents an improvement in resolution of nearly three times over the previous Cassini image release of Titan. The superimposed coordinate system grid in the accompanying image at right illustrates the geographical regions of the moon that are illuminated and visible, as well as the orientation of Titan. North is up and rotated 25 degrees to the left. The yellow curve marks the position of the boundary between day and night on Titan.

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After nearly seven years of space travel, the Cassini-Huygens spacecraft will arrive at Saturn on June 30. In a maneuver called orbit insertion, Cassini will slow itself to enter into orbit around the ringed planet.

Courtesy of NASA/JPL/Space Science Institute