An asteroid large enough to wipe out a continent could potentially collide with the Earth in 2014, astronomers said today. Mark Henderson, Science Correspondent, left, reports on whether the human race faces the same fate as the dinosaurs.

What is the asteroid?

Known as 2003 QQ47, it was discovered on August 24 by the Lincoln Near Earth Asteroid Research Program (LINEAR) in Socorro, New Mexico. Early calculations of its orbit show that it will pass very close to the Earth on March 21, 2014 – and that there is at least a theoretical possibility of a collision.

Should I be concerned?

There is no reason to prepare for Armageddon just yet. The chances of an impact are remote, at just one in 909,000, and the odds of oblivion will lengthen still further as more details of the object's orbit become known.

Astronomers have given it a value of one on the Torino Scale, which grades the potential risk to the Earth from zero, signifying no danger, to ten, meaning a catastrophic collision of the sort that wiped out the dinosaurs. A rating of one judges an impact to be "extremely unlikely", but not impossible.

During the first week in which scientists have known of its existence, however, they have been able to observe it only 51 times. This has provided far too little data to estimate its orbit with great accuracy, and astronomers expect to rule out any prospect of a collision as they watch it more closely.

What would happen if it did hit Earth?

If 2003 QQ47, which is 1.2km (1,370 yards) across and has an estimated mass of 2,600 million tonnes, were to strike the Earth, its effects would be devastating.

The rock is ten times smaller than the one that landed at Chicxulub in Mexico 65 million years ago, causing the climatic disaster that led to the extinction of the dinosaurs, but it would still release enough energy to lay waste a continent.

It would strike the Earth at 75,000 miles an hour, exploding with a force equivalent to 350,000 megatonnes of TNT – around eight million times greater than the atomic bomb dropped on Hiroshima.

How often do asteroids strike Earth?

While this asteroid is very unlikely to hit the Earth, it is certain that one will do so at some point in the future. Asteroids up to 100 metres across strike approximately once every 50 to 1,000 years, and can cause severe local devastation – as is thought to have happened at Tunguska in Siberia in 1908.

Larger objects, capable of causing regional devastation, strike every 1,000 to 100,000 years, and ones more than a mile across, which can cause "nuclear winter" effects, hit still less frequently.

Can anything be done to stop a strike?

Scientists believe that, given sufficient warning of an impending impact, it should be possible to divert an asteroid's path to take it away from Earth.

One approach would be to explode a nuclear bomb on or close to the asteroid, as in the film Armageddon, to nudge it into a more favourable orbit. This, however, is a high-risk strategy that could itself cause disaster: there is a strong possibility that the explosion would blast the asteroid into thousands of smaller pieces, each of which would be a threat to the Earth in its own right.

Another idea is to use lasers, either mounted on the Moon or orbiting the Earth like the Hubble Space Telescope, to burn off sections of the asteroid and alter its orbit.

A similar effect might also be achieved by "painting" the rock. The speed and trajectory of an asteroid depends in part on its temperature – a phenomenon known as the Yarkovsky effect – and this can be changed by altering the amount of heat it absorbs from the Sun. If a method was devised of painting the asteroid with a reflective coating, it could, given enough time, divert it away from the Earth.

A fourth possibility is to nudge the asteroid away using a giant airbag. A spacecraft would carry the uninflated airbag to the asteroid, then start a chemical reaction to fill it with gas. As the bag inflated, it would push the asteroid away and into another orbit.

Is it worth a flutter?

The bookmaker William Hill said it would be happy to take bets at odds of 909,000 to one that the asteroid would hit. It says it is happy to do so on the principle that if the asteroid does wipe out life on Earth, it will probably not have to worry about paying out to winning customers.

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