If an object was sent to strike the asteroid, the rock's course could be subtly changed
Throughout geological history, our planet has been hit by a succession of major asteroids and the probabilities suggest further impacts will occur in the future.
No-one can say today when these might happen; we haven’t yet identified an asteroid of sufficient size and on a path that gives us immediate cause for concern.
But the evidence hints strongly that something could find us sooner or later, and we need to be ready.
On average, an object about the size of car will enter the Earth's atmosphere once a year, producing a spectacular fireball in the sky.
About every 2,000 years or so, an object the size of a football field will impact the Earth, causing significant local damage.
And then, every few million years, a rock turns up that has a girth measured in kilometres. An impact from one of these will produce global effects.
Edited by Belial, 31 October 2010 - 09:31 AM.