Chelyabinsk asteroid glowed at 30x strength of sun When a massive asteroid exploded over the Russian city of Chelyabinsk on Feb. 15, 2012, it injured more than 1,200 people and damaged hundreds of buildings. In the nine months since the asteroid exploded, researchers led by the Russian Academy of Sciences have visited 50 villages in the surrounding area to assess the damage it caused. Security and amateur video footage helped them trace the path of the fireball as it streaked across the sky. Meteorites strike Russia, hundreds injured Their investigation, to be published Nov. 7 in the journal Science, showed that the explosion caused a shockwave strong enough to knock people off their feet. The damage spread up to 55 miles around the point of impact, as the shockwave shattered windows in 3,600 apartment blocks and collapsed a factory roof. The asteroid reached its brightest and hottest -- glowing 30 times brighter than the sun -- a mere 18 miles from the ground. The glow left observers with retina and skin burns -- one resident, who made the mistake of looking at the asteroid from 18 miles away, later lost skin due to the radiation burns. It reached a peak speed of 11.6 miles per second -- or more than 40,000 miles per hour. When it started exploding some 28 miles from the ground, it created the largest airburst on the planet since 1908, when another asteroid caused an airburst near the Podkamennaya Tunguska River. The airburst had the force of 400 to 600 kilotonnes of TNT, according to another study, published in Nature. Aftermath of close encounter with meteor In a third study on the asteroid, also published in Nature, Jiri Borovicka of the Academy of Sciences of the Czech Republic mapped the orbit of the meteor, showing that it was once likely part of asteroid 86039. The Russian Academy of Sciences study went on to say the rock core shows that the asteroid represents a type of meteorite called an LL chondrite. That is the same as the space asteroid Itokawa. The Japanese space asteroid probe Hayabusa collected samples of Itokawa in 2011, the findings of which are helping researchers better understand the Chelyabinsk asteroid. The researchers believe the asteroid started at about 19.8 meters in diameter, though that estimate may have varied up to 4.6 meters in either direction. By the time it reached the ground, tearing through the frozen surface of Lake Chebarkul, it left a hole just 7 meters wide. Only about .05 percent of the actual meteor made it to Earth, as the rest burned under the intense heat. The largest chunk -- the one that left the 7-meter hole -- weighed 650 kilograms. It was recovered from the lake in October.