Astronomers think they may have discovered the solar system's 10th planet.
Two separate teams of scientists -- one in Britain, one in the United States -- will present evidence next week of a massive new object in the furthest reaches of the solar system.
But though there are a remarkable number of similarities between the team's findings, there are enough differences to cast doubt on the discovery.
John Murray of the Open University in Britain and John Matese of the University of Louisiana at Lafayette agree that there is something way out there beyond Pluto. Whatever it is, it's huge; astronomers think it is three to six times the size of Jupiter, the largest planet in the solar system.
However, Murray and Matese disagree on the angle of the object's orbit. This means they are either describing two separate objects, which seems unlikely, or there is another explanation altogether for the comet's anomalous movement.
Whatever it is, Matese believes the object orbits the Sun every four million years and is about 10 times farther out than Pluto, or roughly 25,000 astronomical units (one astronomical unit is the distance between the Earth and the Sun).
Murray estimates the object is 32,000 astronomical units out and orbits every six million years, or one inch every four years, moving in the opposite direction to all the other planets in the solar system.
Both astronomers detected the object by studying anomalies in the orbits of comets that pass through the birthplace of comets, the Oort Comet Cloud.
Matese said the object is either a brown dwarf -- a sun that didn't reach ignition mass -- or a planet from another solar system that wandered into our own, an opinion shared by Murray.
It is unlikely to have formed at the same time as the other planets in the solar system, Matese said, and therefore doesn't conform to the strict definition of a planet.
"The difference is significant," said Matese. "We're talking about two different things. It's not as though we're absolutely confident there's an object out there [but] it's the only rational explanation."
Matese said he'd been studying comets in the Oort Cloud for the better part of a decade. About three years ago, he noticed something strange about a comet's behavior but resisted the idea that it was caused by a massive object until he eliminated other possibilities.
Though extremely faint, the object may be detected by the next generation of radio and infrared space telescopes, Matese said. Pluto, the solar system's most distant planet, wasn't discovered until 1930 by American astronomer Clyde Tombaugh.
Murray's findings will be published next week in the Monthly Notices of the Royal Astronomical Society, while Matese will publish in forthcoming issue of the journal Icarus.
