Asteroid Buzzes Earth in Record-Breaking Flyby

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Corbis

Cosmic shooting gallery

There are lessons to be taken from today's asteroid flyby and fireball blast, researchers said.

"Today's events, both with 2012 DA14 and the Russian meteorite, are a reminder that our solar system is a crowded place," Chris Lewicki, president of asteroid-mining firm Planetary Resources, wrote in a blog post today.

Our planet has indeed been pummeled by asteroids many times over its history — perhaps most famously 65 million years ago, when a 6-mile-wide (10 km) behemoth wiped out the dinosaurs — and it will continue to be struck in the future.

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The good news is that we probably don't have to worry about a potential civilization-ending strike anytime soon. NASA researchers have mapped out the orbits of 90 percent of the biggest and most dangerous near-Earth asteroids, and none of them seem to be on a collision course with Earth in the foreseeable future.

But there are a lot of smaller space rocks out there waiting to be discovered and mapped. Researchers have identified just 9,600 near-Earth asteroids to date, but they think a million or more are likely to be out there. (2012 DA14 itself was just discovered in February 2012.)

Spotting the most threatening of these space rocks may require lofting dedicated asteroid-hunting space telescopes, researchers say. The nonprofit B612 foundation plans to do just that; in 2017 or 2018, it aims to launch an instrument called the Sentinel Space Telescope, which would scan Earth's neighborhood from a Venus-like orbit, freeing it from having to contend with the glare of the sun.

Astronomers estimate that asteroids the size of 2012 DA14 buzz Earth this closely every 40 years and hit our planet once every 1,200 years or so. If 2012 DA14 did hit us, it would probably cause severe destruction on a local scale. In 1908, a space rock thought to be of similar size exploded over Siberia, flattening about 825 square miles (2,137 square km) of forest.

This article originally appeared on SPACE.com.

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