In January, NASA scientists spotted a mysterious X-shaped object hurtling through the asteroid belt between Mars and Jupiter. They believed the object, named P/2010 A2, was the result of a recent asteroid collision, a rare sight. They were only partially right.
According to Discovery News, Hubble scientists who have been tracking the debris now say the collision probably occurred in February or March of 2009. "We expected the debris field to expand dramatically, like shrapnel flying from a hand grenade," said David Jewitt, who lead the Hubble observation. "We found that the object is expanding very, very slowly and that it started not a week but nearly a year before our January observations."
Jewitt believes P/2010 A2 is the result of a collision between a large asteroid and smaller asteroid traveling more than 3 miles per second, writes Wired.com. "The energy," Jewitt said, "would have been comparable to a small atomic bomb, maybe a kiloton of TNT."