Out in the asteroid belt beyond Mars, two asteroids rendezvous-ed in the darkness, with explosive results. Atomic bomb level explosive. These two asteroids, one probably 400 feet wide and the other, smaller asteroid around 10 to 15 feet across, collided sometime in early 2009. This is the first time we humans have observed an asteroid impact right after it has occurred, and the first time a resulting x-shape has been seen. Researchers aren't sure what caused the novel shape, and they were surprised by how long the dust tail has lasted. The analysis of the finding, originally announced earlier this year, is published in Nature this week. From Phil Plait, DISCOVER's Bad Astronomer:
This is a false-color image showing the object, called P/2010 A2, in visible light. The long tail of debris is obvious; this is probably dust being blown back by the solar wind, similar to the way a comet’s tail is blown back. What apparently has happened is that two small, previously-undiscovered asteroids collided, impacting with a speed of at least 5 km/sec (and possibly faster). The energy in such a collision is like setting off a nuclear bomb, or actually many nuclear bombs! The asteroids shattered, and much of the debris expanded outward as pulverized dust.
