When astronomers discovered a mysterious X-shaped object in space last January, they initially thought it was a comet. Further investigation by the Hubble Space Telescope revealed it to be the aftermath of two asteroids smashing into each other.
The discovery of object P/2010 A2 marks the first time astronomers have seen the remains of an asteroid collision; large-scale smash-ups are rare and small collisions can be difficult to spot. Even though astronomers first noticed P/2010 A2 in January, the traces of the collision lingered for months — UCLA astronomer David Jewitt notes that the asteroids' debris fanned out slowly, rather than pinballing across the solar system. Observing the asteroids' remains is incredibly useful, as the objects' deterioration offers insights into the movement of dust throughout space.
Astronomers suspect a rock maybe 10-16 feet (3-5 meters) wide slammed into a larger asteroid at speeds of about 11,200 mph (18,000 kph) with a detonation as powerful as a small atomic bomb, said researcher David Jewitt.
[...Said Jewitt] "These observations are important because we need to know where the dust in the solar system comes from, and how much of it comes from colliding asteroids as opposed to 'outgassing' comets," Jewitt said. "We can also apply this knowledge to the dusty debris disks around other stars, because these are thought to be produced by collisions between unseen bodies in the disks. Knowing how the dust was produced will yield clues about those invisible bodies."[...]
Good thing we have these Hubble bigwigs around. Given P/2010 A2's shape, I would've just dismissed it as the corpse of the Galactic Golem after Superman tossed him into the sky.
[Photos via NASA, ESA, and D. Jewitt @ UCLA]