Rocks in space have been banging into each other as long as there have been rocks in space. We've seen a comet crash into a planet (Shumacker-Levy 9 into Jupiter), we've seen comets fly into the sun, and we've seen meteorites fall to Earth. All of these involve small objects--comets and meteors--interacting with large ones--planets and the sun. But we've never seen two small objects banging into each other*. Till now.
Last week, on January 25 and 29, the mighty and majestic Hubble Space Telescope took pictures of a comet-like object called P/2010 A2. The X like lines coming off the comet (detail) are unlike anything ever seen and are believed to be the debris from a tiny asteroid hitting P/2010 A2.
Space is a very big empty place, but it is also a very violent place. It is only very recently that we have had tools like the Hubble Space Telescope that allow to see some of that violence. Every crash and bang (silent bang, of course) that we can see adds to our knowledge of how the universe works.
* We do have images of a projectile fired from the Deep Impact satellite hitting comet 9P/Tempel 1. But that was a controlled, man-made impact. This is the first natural event we have caught, and therefore much cooler.