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An asteroid that is 400m (1,300ft) wide has passed by Earth, much to the delight of astronomers.

Although invisible to the naked eye, scientists said they spotted strange structures on its surface as it spun past at 30,000mph (48 280.32 km/h).

Asteroid 2005 YU55's was the closest an asteroid has been to Earth in 200 years, according to Nasa.

It is also the largest space rock fly-by Earth has seen since 1976; the next visit by a large asteroid will be 2028.

The aircraft-carrier-sized asteroid was darkly coloured in visible wavelengths and nearly spherical, lazily spinning about once every 20 hours as it raced through our neighbourhood of the Solar System.

Ron Dantowitz, the director of the Clay Centre Observatory in Massachusetts, followed the asteroid through a telescope.

"We're tracking the asteroid itself, so the stars are moving by in the background and the asteroid is actually streaking by at about 30,000mph," he said.

"As we track it, it looks like the stars are moving in the background and the asteroid is locked on in the centre view.

"It's not so much that we can see it tumbling like a rock in space, we're examining it for the brightness and colour."

Read more: http://www.bbc.co.uk/news/science-environment-15572634