Russian Meteor 15/02/13
News reports have recently come in of a huge meteor exploding in the air over the Russian cities of Yekatarinburg and Chelyabinsk (about 200km apart), injuring hundreds of people. It’s worth clarifying some of the facts in this matter:
The object that exploded was a meteor, a lump of space rock passing through the Earth’s atmosphere. In this particular case the meteor appears to have exploded around 10km above the ground, over the city of Chelyabinsk.
The shockwave from the explosion damaged some buildings, shattered windows, and set off car alarms. It appears that most of the injuries came from the broken glass, not from the meteor itself hitting anyone.
Showers of fragments from the meteor have been reported too, falling after the explosion over a large area of Russia.
The meteor poses no risk to us any more; it’s all burned up, and it was a one-off random event. Such things are not that rare, happening once every few years, but this one just happened to fall over a populated area.
This meteor was unrelated to asteroid 2012 DA14 that is due to pass by the Earth later today.
UPDATE: A 6m diameter crater has been found in the ice & snow of Lake Chebarkul where the meteorite is thought to have landed:
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There is always the possibility of larger meteorites hitting the Earth. Are the governments doing everything they could to develop the technology to detect and destroy these meteorites before they hit the ground?
Doing everything they could? No. Only about 10% of all potentially destructive asteroids have been found and tracked, leaving a lot we don’t know anything about.
Their rationale is that these are once per century events, and even then there’s a very low chance (1%) that they’ll impact near / above a heavily populated area, and so they’re not a pressing threat.
To calculate the likelihood per year of anything like this happening over a big city you multiply 0.01 (one per century = 0.01 per year) by 0.01 (% of Earth’s surface that’s urbanised) to get 0.0001, or a 0.01% chance per year.
That seems tiny, but multiply it by the potential loss of life from a large rock (like the one that exploded over Tunguska in 1908) which, if exploding over a city, could kill hundreds of thousands and the number of people that die per year from meteor explosions is quite high. Usually it’s absolutely zero, but once every so often (every 10,000 years maybe) it’s very high indeed.