An asteroid half the size of a football pitch made the closest pass ever observed from Earth on Friday, some 28,000 kilometres above Indonesia, NASA said.
The near-Earth object, named 2012 DA14 after it was discovered last year by astronomers from an observatory in La Sagra in southern Spain, is 45 metres in diameter.
The asteroid is large enough to potentially devastate a large city if it struck Earth, which NASA scientists have ruled out.
The fly-by came the same day a meteor broke apart in the atmosphere over central Russia, injuring around 1,000 people as a shockwave blew out windows and collapsed some walls.
The two events were not related. NASA said the meteor was still being analysed, but that it had travelled from north to south, while the asteroid is moving on an opposite course from south to north.
“According to NASA scientists, the trajectory of the Russian meteorite was significantly different than the trajectory of the asteroid 2012 DA14, making it a completely unrelated object,” NASA said.
DA14 is roughly comparable in size to the meteor believed to have caused the 1908 Tunguska event, when a massive blast laid waste to 2,000 square kilometres of uninhabited Siberian forest — an area somewhat larger than London.
DA14 is likely a similar silicate rock as the Tunguska meteor and would probably explode in the atmosphere if it were bound for Earth.
DA14 passed within 27,650 kilometres of Earth at 1924 GMT and was visible with the aid of binoculars or a small telescope from much of the eastern hemisphere, NASA scientists said.
Under clear night skies, it appeared as a pinpoint of light moving against the stationary background of distant stars.
The flyby at bullet speed — 7.8 kilometres per second — was the closest by such a large object in the decades since astronomers began cataloguing near-Earth objects. It is the closest among upcoming asteroid passes projected for the century ahead.
Donald Yeomans, head of near-Earth objects at NASA’s Jet Propulsion Laboratory, called it “the closest encounter that we’re aware of” by an object in the range of 20 to 120 metres in diameter.
The asteroid’s path was charted precisely enough to rule out collision with Earth, NASA said.
