Last week, as astronomers around the world turned their attention toward the passing asteroid 2012 DA14, a meteorite entered Earth's atmosphere and broke up over Chelyabinsk, Russia. The blast shattered windows and injured hundreds in the small town.
The European Space Agency (ESA) today announced that it is studying the event, which isn't quite as rare as humans might hope. Astronomers predict an event of this sort may happen every "several of tens to 100 years."
This particular meteorite was around 17 meters wide when it entered Earth's atmosphere, traveling at around 18 kilometers per second (around 40,000 miles per hour). It exploded around 15 to 20 kilometers above the planets surface with the force of a 500 kiloton bomb. That's around 30 times the energy released by the atomic bomb detonated over Hiroshima.
In a statement, Detlef Koschny, head of the Near-Earth Object activity division of the ESA's Space Situational Awareness (SSA) program, said that the meteorite was unrelated to the passing of 2012 DA14. This was determined due to the trajectory of the meteorite and the time of its impact in relation to the passing asteroid.
"The terminal part of the explosion probably likely occurred almost directly over Chelyabinsk. This was perhaps the single greatest contributor to the blast damage," said Koschny. "As the explosion and fireball progressed along a shallow trajectory, the cylindrical blast wave would have propagated directly to the ground and would have been intense."
Koschny stated that the airburst was the likely cause of most of the damage seen, and that window damage is expected starting at air pressures of 10 to 20 times normal air pressure.
(Image courtesy Eumetsat/ESA)