March 16, 2014 - Scientists were today warning of a possible asteroid collision with the Earth.
An asteroid around two-thirds of a mile wide (1.2km) could hit the earth on March 21, 2014 and has been classified as "an event meriting careful monitoring" by astronomers.
But they say the probability of the asteroid hitting Earth is just 1 in 909,000 and the risk of impact is likely to decrease as they collect more information.
The newly-discovered asteroid, known as 2003 QQ47, has a mass of around 2,600 million tons (2,600 billion kg).
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 NEO (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."
The giant rock was first observed on August 24 by Lincoln Near Earth Asteroid Research Program (LINEAR), based in Socorro, New Mexico.
The observations were reported to the Minor Planet Centre in Massachusetts, a centre for all new discoveries of asteroids and comets. The asteroid has been given a classification - known as a "Torino hazard rating" of one - defining it as "an event meriting careful monitoring."
Scientists said it was likely to drop down the scale for hazard as more observations were made.
Kevin Yates, project manager for the UK NEO Information Centre, said: "As additional observations are made over the coming months, and the uncertainties decrease, asteroid 2003 QQ47 is likely to drop down the Torino scale.
"The NEO Information Centre will continue to monitor the latest results of observations and publish regular updates on our website."
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.