February 15, 2013 9:53 am
Overnight, a massive meteor—estimated to weigh around ten tons—arced through the early-morning sky over the Russian city of Chelyabinsk. After speeding along at up to 15 to 20 kilometers per second (33,500 to 45,000 miles per hour), says the Russian Academy of Sciences, the meteor broke up overhead. Whether through speed-induced shock wave or mid-air explosion, the meteor shattered windows across the region—the damage injured at least 500 people, says the Associated Press, with 34 people now in the hospital.
There was panic. People had no idea what was happening. Everyone was going around to people’s houses to check if they were OK,” said Sergey Hametov, a resident of Chelyabinsk, about 1,500 kilometres east of Moscow, the biggest city in the affected region.
Though such gripping video is rare, exploding meteors themselves are not. According to the AP, smaller meteor strikes happen “five to 10 times a year,” with ones on the scale of today’s Russian meteor lighting up every five years or so. The most recent similar event was a 2008 meteor that exploded over Sudan, while in Russia itself, a similar event took place in 2002.
As for understanding how or why a meteor might explode with such force, rather than just plowing into the ground, says Ethan Siegel for his blog Starts With a Bang!, it often comes down to just a little bit of water or carbon dioxide:
When a meteor enters Earth’s atmosphere, it’s moving very, very quickly relative to the Earth. Meteors have a speed relative to Earth anywhere between about 40,000 and 260,000 kilometers-per-hour (11 to 72 kilometers/second), which is incredibly fast. The Earth’s atmosphere works — through friction — to slow this meteor down, heating it up and causing it to glow.
But if there’s a lot of ice and/or frozen carbon dioxide in this meteor, it’s going to heat up and start to boil. If you have a solid piece of rock with a cavern of boiling water inside, it’s only a matter of time before the pressure builds up enough to cause a powerful explosion.
The AP reports that fragments of the meteor have fallen into a reservoir outside the nearby town of Chebarkul. Analyzing these fragments should give a better sense of what the meteor was made of, and maybe where it came from. For now, the guess is that the meteor was mostly made of iron.
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