Airburst Explained: NASA Addresses the Russian Meteor Explosion

A small asteroid entered Earth's atmosphere early Friday, February 15, 2013 over Chelyabinsk, Russia at about 9:20 am local Russian time. Initial estimates, according to Bill Cooke, lead for the Meteoroid Environments Office at NASA's Marshall Space Flight Center, is that the asteroid was about 15 meters (50 feet) in diameter, with a weight of