Averting Armageddon, BBC Documentary, Horizon

The Earth is under constant bombardment. Each year, many fragments of debris hit our planet. Fortunately for us, most are so small that they burn up harmlessly in the atmosphere. The scarred surface of the Moon Image courtesy of Mike Whitecross The scarred surface of the Moon tells us it has been hit many times However, there are hundreds of larger asteroids orbiting near the Earth. Many scientists now believe that one of these hit the Earth 65 million years ago, killing the dinosaurs, along with 90 of all life on the planet. What is more, it is only a matter of time before the Earth is hit again.