Asteroid homing in for Earth's closest near-miss

Key points

• An asteroid the size of a house is to pass within 26,000 miles of Earth

• Asteroid discovered during a routine survey

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• Travelling at 10 miles/sec, it will be visible with binoculars or small telescope

Key quote: "The likelihood of an impact big enough to destroy a city is about once per 1,000 years, which is in the span of recorded human history." Dr John Davies, Royal Observatory of Edinburgh.

Story in full: ASTRONOMERS were last night waiting to see an asteroid the size of a house pass just 26,500 miles from Earth, the closest near-miss on record by a space rock.

The asteroid, which was first spied on Monday night and is travelling at ten miles a second, was not thought to be bright enough to spot with the naked eye, but should be close enough to be seen using a small telescope or binoculars.

Although 26,000 miles is roughly the Earth’s circumference, it is a mere whisker in space terms, said Dr John Davies, an astronomer at the Royal Observatory of Edinburgh. The last such near-miss was in December 1994, according to the Near Earth Object Information Centre (NEOIC) in Leicester.

Dr Davies said: "We are not scared of this one because we know exactly where it is going, but it is beyond doubt that the Earth has been struck by asteroids in the past and it is certain that it will be struck again in the future.

"The likelihood of an impact big enough to destroy a city is about once per 1,000 years, which is in the span of recorded human history."

Experts advising the NEOIC say the object, known to astronomers as 2004 FH, is no danger to Earth but will provide an opportunity for amateur astronomers to catch a glimpse of an asteroid. At its closest point, it will seem to be streaking over the southern Atlantic Ocean. Similar-sized asteroids are thought to come close to Earth on average once every two years, but have previously escaped detection.

Steve Chesley, an astronomer at NASA’s Jet Propulsion Laboratory, said: "The important thing is not that it’s happening, but that we detected it."

Astronomers found the asteroid during a routine survey using a pair of telescopes in New Mexico funded by NASA. "It immediately became clear it would pass very close by the Earth," Mr Chesley said.

Astronomers have not ruled out that the asteroid and our planet could meet again sometime in the future.

"Something this size would probably break up in the atmosphere into a bright fireball or a bright shooting star and then a few boulders would drop on to the ground somewhere," said Dr Davies.

"Small asteroids come into the earth’s orbit all the time, but we have become increasingly good at detecting them because of new technology, telescopes with better detectors that can cover more sky more quickly. Now it is possible to scan the whole sky in one night, where a couple of years ago that just wasn’t possible."

Until recently, no-one took the asteroid threat very seriously. But in 1994, the comet Shoemaker-Levy 9 hit Jupiter, creating an explosion the size of the Earth. It was the first time a collision between two astronomical bodies had been observed. Some astrologers warned that if Jupiter had been hit, the Earth could be next.

There has been pressure on the British and US governments to fund systematic skywatches to warn of potentially dangerous collisions. There is no dedicated programme searching for asteroids approaching the southern hemisphere, and NASA only looks for bodies bigger than a kilometre across.

An asteroid seven miles wide that hit the Yucatan peninsula 65 million years ago, in what is now Mexico, is widely accepted to have caused the extinction of the dinosaurs. And an asteroid about 60 yards across landed at Tunguska in Siberia in 1908, flattening trees for 13 miles and killing hundreds of reindeer.

Had that impact been in the centre of London, everything inside the M25 would have been destroyed.