WASHINGTON: In a close shave, an asteroid about half the size of a football field will miss Earth by 27,680

on February 15, the closest asteroid in recorded history to buzz past our planet, NASA scientists say.

kilometres"This is a record-setting close approach," said Don Yeomans of NASA's Near Earth Object Program at Jet Propulsion Laboratory "Since regular sky surveys began in the 1990s, we've never seen an object this big get so close to Earth," Yeomans said.The asteroid dubbed 2012 DA14 is a fairly typical near-Earth asteroid. It measures some 50 metres wide, neither very large nor very small, and is probably made of stone, as opposed to metal or ice.Yeomans estimated that an asteroid like 2012 DA14 flies past Earth, on average, every 40 years, yet actually strikes our planet only every 1200 years or so.The impact of a 50-metre asteroid is not cataclysmic unless you happen to be underneath it, Yeomans said.He pointed out that a similar-sized object formed the mile wide Meteor Crater in Arizona when it struck about 50,000 years ago."That asteroid was made of iron which made it an especially potent impactor," he said in a statement.Also, in 1908, something about the size of 2012 DA14 exploded in the atmosphere above Siberia, levelling hundreds of square miles of forest."2012 DA14 will definitely not hit Earth. The orbit of the asteroid is known well enough to rule out an impact," said Yeomans.NASA radars will be monitoring the space rock as it approaches Earth closer than many man-made satellites.Yeomans said the asteroid will thread the gap between low-Earth orbit, where the International Space Station (ISS) and many Earth observation satellites are located, and the higher belt of geosynchronous satellites, which provide weather data and telecommunications."The odds of an impact with a satellite are extremely remote," he said."The asteroid will be racing across the sky, moving almost a full degree (or twice the width of a full Moon) every minute. That's going to be hard to track," Yeomans said.