Bruce Murray Space Image Library
Collision in the Main Belt
Later in the same month, when the Hubble Space Telescope's new Wide Field Camera 3 was trained on the body, called P/2010 A2, astronomers discovered an X-shaped debris pattern that is almost certainly the aftermath of a collision between two previously undetected asteroids. Although the asteroid belt contains many thousands of objects, they are separated by wide regions of empty space, and no collision has ever before been observed. Hubble repeatedly observed P/2010 A2 through the rest of the year and found the debris field to be expanding very slowly, which means that the collision must have happened in February or March of 2009.