2:07pm UK, Tuesday September 02, 2003

Scientists monitoring an asteroid have warned it could collide with Earth in just over a decade.

180 ozone cloud space creditNASA VISIBLE EARTH.jpg

Target: Earth, picture by Nasa

The newly discovered asteroid, known as 2003 QQ47, is around two-thirds of a mile wide and has been classified as "an event meriting careful monitoring" by astronomers.

It is around one tenth fo the size of the meteor that is thought to have wiped out dinosaurs on Earth 65 million years ago.

In the event of it hitting the Earth, the rock would have the force of 350,000 mega tonnes - around eight million times more powerful than the bomb dropped at Hiroshima at the end of the Second World War.

On impact it would be travelling at 75,000 miles a hour.

Experts say the giant rock, which was first spotted by Lincoln Near Earth Asteroid Research Program (Linear) in New Mexico, could impact on Earth on March 21, 2014.

But they say the probability of the asteroid hitting Earth is just one in 909,000 and the risk of impact is likely to decrease as they collect more information.

With a mass of around 2,600 million tons, it has been given a "Torino hazard rating" of one. Scientists said it is likely to drop down the Torino hazard scale as more observations are made.

Its orbit calculations are currently based on just 51 observations during a seven-day period.

Dr Alan Fitzsimmons of Queen's University, Belfast, one of the expert team advising the UK Near Earth Objects Information Centre, based in Leicester, said: "The NEO will be observable from Earth for the next two months, and astronomers will continue to track it over this period."

He added that there is no cause for concern over the asteroid.

Asteroids such as 2003 QQ47 are chunks of rock left over from the formation of our solar system 4.5 billion years ago.

Most are kept at a safe distance from Earth in the asteroid belt between the orbits of Mars and Jupiter.

But the gravitational influence of giant planets such as Jupiter can nudge asteroids out of these safe orbits and send them plunging into the Earth's neighbourhood.