3:20pm UK, Friday June 21, 2002

An asteroid the size of a football pitch has just missed the Earth in one of the closest ever near misses.

The space rock passed well within the orbit of the Moon and missed Earth by only 75,000 miles.

sl asteroid space rock nasa near-miss

Rock passed before being spotted

Had it struck a built up area the damage and loss of life would have been similar to that caused by a large H-bomb.

Not detected

The asteroid, given the name 2002MN, was travelling at more than 23,000 mph when it was spotted by astronomers in New Mexico, USA.

It was not detected until three days after it came so perilously close to the Earth on Friday last week.

2002MN was only the sixth asteroid known to have penetrated the Moon's orbit, and by far the biggest.

Although a lightweight compared with some asteroids, the rock was big enough to have caused local devastation similar to an impact that occurred in Siberia in 1908.

'Close shave'

On that occasion an asteroid which exploded above Tunguska flattened 2,000 square kilometres of forest.

The asteroid, which had a diameter of between 50 and 120 metres, was detected by astronomers from the Lincoln Laboratory Near Earth Asteroid Research Project.

Brian Marsden, from the Harvard-Smithsonian Center for Astrophysics said: "It was a close shave."

Currently there is no dedicated programme searching for NEOs approaching the southern hemisphere, and the American space agency Nasa only looks out for bodies bigger than a kilometre across.