Comet impostor ID'd as asteroid: Hubble and Rosetta images undo space rock's disguise.
The fuzzy body with the long, bright tall spotted by astronomers in January was a dead ringer for a comet. But the object's location put that notion on the rocks: The body lies in the innermost part of the asteroid belt between Mars and Jupiter, in an orbit that no comet could have.
Instead, researchers have identified the body dubbed P/2010 A2 as a 120-meter-wide asteroid, the remnant of a slightly larger space rock that was recently hit by a much tinier denizen of the asteroid belt. The unseen collision vaporized the smaller body and stripped material from P/2010 A2, creating the debris initially mistaken for a comet's tail.
Astronomers initially thought the suspected collision occurred just weeks before the asteroid was spotted. But new images from the Hubble Space Telescope and the Rosetta spacecraft reveal that the dusty debris from the smashup is expanding sedately rather than flying off like shrapnel, indicating that the collision occurred about a year before P/2010 A2 was sighted, two teams of astronomers report in the Oct. 14 Nature.
Although not as recent as astronomers had thought, the smashup is new enough to "open the door to the empirical study of the way asteroids die," says David Jewitt of UCLA, the lead author of the report analyzing Hubble images.
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|Title Annotation:||Atom & Cosmos|
|Article Type:||Brief article|
|Date:||Nov 6, 2010|
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