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Last Updated: Tuesday, 4 July 2006, 10:05 GMT 11:05 UK
Asteroid makes close Earth flyby
Asteroid Mathilde captured by the Near spacecraft
Several asteroids have been photographed by spacecraft

A giant space rock whizzed past the Earth on Monday under the close scrutiny of astronomers.

The mountain-sized object had been classed as a "potentially hazardous asteroid", but scientists said it posed no danger to Earth.

The asteroid 2004 XP14, as it is has been designated, was visible through good amateur telescopes.

Its closest approach to Earth, above the west coast of North America, occurred at 0444 GMT.

At this time calculations suggested it was about 432,709km (268,873 miles) from the Earth, only 1.1 times the planet's distance from the Moon.

Radar analysis

Scientists were using the occasion to work out the precise size and shape of the object by bouncing very high frequency radio waves off its surface.

Space rocks larger than about 100m that come closer to Earth than 7.5m km
Astronomers have spotted 796 so far in this category
They are under close scrutiny to better predict any threat
It will allow them to calculate precisely how close it came to the planet, as well as its velocity and mass, giving clues to its composition and structure - and future course.

2004 XP14 was discovered in December 2004 by telescopes run by the Lincoln Near Earth Asteroid Research (Linear) project.

Funded by the United States Air Force and the US space agency (Nasa), Linear aims to survey the sky for potentially dangerous asteroids.

Initially, there were concerns that asteroid 2004 XP14 might hit Earth later this century. But after further monitoring, astronomers ruled out such a collision for the foreseeable future.

"It's not Earth-threatening," said Don Yeomans, who heads Nasa's Near Earth Object Program.

Mountain-sized rock passes Earth
29 Sep 04 |  Science/Nature
Relic of ancient asteroid found
10 May 06 |  Science/Nature
Gravity tug to deflect asteroids
09 Nov 05 |  Science/Nature

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