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The largest asteroid impact on Earth in a century
Main mass of the Chelyabinsk fall at the Chelyabinsk State Museum of Local History shortly
after recovery from Chebarkul Lake. Photo courtesy of Andrey Yarantsev. For more information,
please see Figure S53D in the Supporting Online Material.
[Image courtesy of Science/AAAS]
Earlier this year, on 15 February, an asteroid violently exploded above the city of Chelyabinsk, Russia. It caused the largest airburst, or explosion, on the planet since a similar event occurred back in 1908 (also in Russia). And since it happened in a heavily populated area, where cell phones, video cameras and other recording devices are common, researchers have been able to gather a tremendous amount of information about it.
Olga Popova and colleagues visited 50 villages around Chelyabinsk in the weeks that followed the violent airburst and collected data on the asteroid that caused it as well as the damage it caused. The researchers used security cameras and dash-cams in peoples' cars to re-trace the fireball's path through the sky. Based on their study, they say that the asteroid's explosion produced a shockwave that was powerful enough to knock people in its path off their feet.
The researchers were able to tell that the shockwave formed about 55 miles (90 kilometers) above the ground—and that the asteroid got the brightest and hottest when it was about 18 miles (30 kilometers from the ground. Popova and the other researchers also counted how many homes were damaged and how many people were either injured by the shockwave or burned by its radiation.
They estimate that the asteroid was originally 19.8 meters wide, even though by the time it reached Earth, it only left a 7-meter-wide hole in the ground. Based on their analysis, they suggest that this Chelyabinsk asteroid was a type of meteorite called an LL chondrite. The data they gathered may help astronomers to better understand other "near-Earth" objects and come up with strategies to protect our planet from them.