As end-of-the-world scenarios go, an apocalyptic collision with an

asteroid or comet is the new kid on the block, gaining respectability only in

the last decade of the 20th century with the realisation that the dinosaurs had

been wiped out by just such an impact.

Now the science community is making up for lost time, with

worldwide efforts to track the thousands of potentially hazardous near-Earth

objects, and plans for high-tech hardware that could deflect an incoming object

from a collision course – a procedure depicted, with little regard for

scientific accuracy, in several Hollywood movies.

Astrophysicist and science writer Andrew May disentangles

fact from fiction in this fast-moving and entertaining account, covering the

nature and history of comets and asteroids, the reason why some orbits are more

hazardous than others, the devastating local and global effects that an impact

event would produce, and – more optimistically – the way future space missions

could avert a catastrophe.