Call it astronomy by YouTube.

Unprecedented social media documentation of a small asteroid exploding over a Russian city earlier this year has taught scientists much more about how and how often such spectacular events happen.

In one of three scientific papers on the Chelyabinsk meteor published Wednesday, a University of Western Ontario scientist concludes that the heavenly bodies are hitting the Earth two or three times more often than we thought.

"The consensus seems to be that we're seeing more things in the tens-of-metre size hitting us than we previously thought," said Peter Brown, lead author of a paper published in Nature. "Our knowledge of the risk is getting better."

The Chelyabinsk meteor sailed into the Earth's atmosphere on Feb. 15 and exploded in the sky so brightly that it cast daytime shadows in the nearby city of that name. The long, fiery trail gave observers plenty of time to whip out smartphones and videocams to record it and many did.

More than 400 recordings of it exist.

"It's almost certainly the best-recorded event in any of our lifetimes," said Brown. "Even if it happens again, the odds are it will happen over the oceans and be virtually unrecorded."

The blast knocked people off their feet and smashed thousands of windows. Many residents of Chelyabinsk were injured from flying glass.

Olga Popova, author of another paper published in Science, used the data from security and dashboard cameras to calculate that the asteroid was nearly 20 metres in diameter and hit a speed of 18.6 kilometres per second. The blast was 30 times brighter than the sun and released energy equivalent to 530 kilotonnes of TNT.

Brown and his colleagues were able to use the wealth of data to construct a clearer picture of what happens to asteroids when they hit the atmosphere.

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YouTube astronomy brings new views on meteors