London, Feb 10 : If reports are to be believed, Earth might be hit by an asteroid in about 160 years time.

According to a report in New Scientist, the asteroid, named 1999 RQ36 was discovered a decade ago, but it was not considered particularly worrisome since it has no chance of striking Earth in the next 100 years.

Now, new calculations show a 1 in 1400 chance that it will strike Earth between 2169 and 2199, according to Andrea Milani of the University of Pisa in Italy and colleagues.

While that might seem a distant threat, there's far less time available to deflect it off course.

With an estimated diameter of 560 metres, 1999 RQ36 is more than twice the size of the better-known asteroid Apophis, which has a 1 in 45,000 chance of hitting Earth in
2036.

Both are large enough to unleash devastating tsunamis if they were to smash into the ocean.

Although 1999 RQ36's potential collision is late in the next century, the window of opportunity to deflect it comes much sooner, prior to a series of close approaches to Earth that the asteroid will make between 2060 and 2080.

The window of opportunity to deflect the asteroid comes much sooner than the potential collision

Asteroid trajectories are bent by Earth's gravity during such near misses, and the amount of bending is highly dependent on how close they get to Earth.

A small nudge made ahead of a fly-by will get amplified into a large change in trajectory afterward.

In the case of 1999 RQ36, a deflection of less than 1 kilometer would be enough to eliminate any chance of collision in the next century.

But after 2080, the asteroid does not come as close to Earth before the potential impact, so any mission to deflect it would have to nudge the asteroid off course by several tens of kilometers - a much more difficult and expensive proposition.

"That's worth thinking about," said Clark Chapman of the Southwest Research Institute in Boulder, Colorado. (ANI)