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The Earth Is Pummeled By Asteroids All the Time; That They’re Not Causing Damage Is Just Luck

Most asteroids explode high up in the air or crash into the ocean, but some don’t

Colin Schultz
04_24_2014_chelyabinsk asteroid.jpg
A fragment of the meteorite that tore through the Earth above Chelyabinsk, Russia, in February 2013. STRINGER/RUSSIA/Reuters/Corbis

The massive meteor that broke up in the air over Chelyabinsk, Russia, in February 2013, was one of the largest in recent memory—a 500 kiloton explosion. But it wasn't the only sizable space rock to pierce the Earth's atmosphere in recent years. According to the observations of the Comprehensive Nuclear-Test-Ban Treaty Organization, 26 large asteroids hit the Earth from 2000 to 2013, each releasing anywhere from 1 to 600 kilotons of energy in the process, reports Jonathan Amos for the BBC.

That these other impacts did not become news was largely a matter of luck. Fortunately for us, most of the asteroids crashed down over the ocean.

The high frequency of asteroid strikes was brought to Amos' attention by the B612 Foundation, an organization that is currently raising money to launch a satellite that would be used to detect and track asteroids—both for Earthly protection, but also for the nascent industry of space mining.

The B612 Foundation put together a video based on the CTBTO's data showing where those 26 asteroids hit.

Most of the asteroids that hit the Earth are nowhere near as big as the one that blew up over Chelyabinsk. Based on a statistical analysis of asteroid size and strike frequency, though, the B612 Foundation suggests that a city-busting, multi-megaton asteroid should hit the Earth roughly once per century, says Amos.

These aren't apocalypse-level asteroids, but they're big enough to cause problems. And, says Sam Machkovech for Ars Technica, current asteroid detection and tracking equipment isn't able to spot most of them. The B612 Foundation thinks their satellite can help, but first it needs to get off the ground.

Yet whether such a project is worth it depends on your perspective, hints Adam Mann for Wired:

A Hiroshima-scale asteroid explosion happens in our atmosphere on average once a year and yet we’re all still here. Moreover, asteroids can’t aim themselves at populated centers. Most of the Earth’s surface is water and even a large percentage of land is fairly uninhabited by humans. Though B612′s Ed Lu mentions in the video that only “blind luck” is preventing a catastrophic city-size space rock from killing us, keep in mind that blind luck has actually been serving us fairly well so far.

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Colin Schultz

Colin Schultz is a freelance science writer and editor based in Toronto, Canada. He blogs for Smart News and contributes to the American Geophysical Union. He has a B.Sc. in physical science and philosophy, and a M.A. in journalism.