Asteroid on course to hit earth

An asteroid more than a mile wide is on course to devastate the earth in 17 years.

Early predictions suggest that NT7 is due to hit on 1 February 2019, and astronomers have given the asteroid a rating on the socalled Palermo technical scale of threat of 0.06, making it the first object to be given a positive value.

From its brightness, astronomers estimate it is about two kilometres wide ? large enough to cause continent-wide devastation on the earth. It circles the sun every 837 days and travels in a tilted orbit from about the distance of Mars to just within the earth?s orbit.

Detailed calculations of its orbit suggest many occasions when its projected path through space intersects that of the earth.

Researchers estimate that in 2019, its impact velocity would be 28km a second - enough to wipe out a continent and cause global climate changes.

Dr Benny Peiser, of Liverpool John Moores University, said: "This asteroid has now become the most threatening object in the short history of asteroid detection."

However, he said more detailed observations in the future could change the situation. He went on: "This unique event should not diminish the fact that additional observations in coming weeks will almost certainly, we hope, eliminate the current threat."

NT7 was first seen on the night of 5 July, picked up by the Linear Observatory's automated sky survey programme in New Mexico. Since then, astronomers worldwide have been paying close attention to it, amassing almost 200 observations in a few weeks.

The asteroid will be easily observable for the next 18 months, so there is no risk of astronomers losing track of it. Observations made over that period - and the fact that NT7 is bright enough that it is bound to show up in old photographs - mean that astronomers will soon be able to calculate a very precise orbit.

Dr Donald Yeomans, of Nasa's Jet Propulsion Laboratory in California, said: "The orbit of this object is rather highly inclined to the earth's orbit. It has been missed because until recently observers were not looking for such objects in that region of space."

He added that it was too early to be certain whether the asteroid would actually collide with the earth. He said: "The error in our knowledge of where NT7 will be on 1 February 2019 is large, several tens of millions of kilometres."

Dr Yeomans said that the world would have to get used to finding more objects like NT7 that, on discovery, look threatening, but later turn out to be harmless. He said: "This is because the problem of Near Earth Objects is now being properly addressed."

A smaller asteroid, about half a mile across, also on a potential collision course with earth in 878 years, was detected in April. Scientists predicted it would not destroy all life on earth but could obliterate a small country, set off massive fires and change global weather.