Understanding What Exploded Over Russia

Two weeks after an asteroid exploded over Russia's Ural mountains, NASA scientists are making progress understanding the origin and make-up of the unexpected space rock. In a one in a million coincidence that still has experts shaking their heads, the small asteroid completely unrelated to 2012 DA14 struck Earth only hours before the publicized event. The most telling information comes from a network of infrasound sensors operated by the Comprehensive Nuclear-Test-Ban Treaty (CTBT). The asteroid was about 17 meters in diameter, weighed about 10,000 metric tons, and struck Earth going about 40,000 mph.