Asteroid gives Earth its closest buzz

An asteroid skimmed past Earth in the closest near-miss ever recorded on Friday night. The space rock – the size of an armchair – came within 5,480 km (3,405 miles) which is less than half the radius of the Earth.

Observatory on Mount Lemmon, Arizona

It flew by over the Pacific and South America before heading out into space again. If it had entered the atmosphere, it would have probably exploded in a brilliant fireball, showering stones into the sea.

The asteroid, labelled 2011 CQ1, was only discovered earlier the same day by robotic telescopes called the Catalina Sky Survey watching for such events from Mount Lemmon in the Arizona desert.

NASA experts said the asteroid was a member of the Apollo class of cosmic missiles that are a threat to Earth. It came so close that the Earth’s gravitational pull permanently shifted its orbit.

But NASA’s Asteroid Watch scientists said on Twitter: “Even if it came closer, a rocky asteroid small as 2010 CQ1 would break apart in our atmosphere and cause no ground damage.”

They estimate that there could be around a billion asteroids of similar size or larger ready to enter near-Earth space at any time. Last month the Wide-field Infrared Survey Explorer satellite, WISE, completed a survey of the sky, having logged 20 previously undiscovered comets, more than 33,000 new asteroids in the main belt between Mars and Jupiter, and 134 near-Earth objects (NEOs) that can come close to the Earth.

A similar-sized asteroid actually crashed to Earth in October 2008, only days after being spotted. It exploded and rained rocks over the Sudan which were later collected by a team of scientists.

The latest asteroid was photographed as a tiny speck against star trails from an observatory in New Mexico.

• Discover space for yourself and do fun science with a telescope. Here is Skymania’s advice on how to choose a telescope. We also have a guide to the different types of telescope available. Check out our monthly sky guide too!

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