13. Colliding worlds

    • At least twenty pieces of a comet hit Jupiter on 7 July 1992, producing explosive fireworks and dark scars that fascinated astronomers throughout the world.

    • Some comets are on suicide missions to the Sun, diving into our star and being consumed by it.

    • Most of the impact craters on the Earth disappeared long ago, but a few of the relatively recent ones have been located from space.

    • An asteroid wiped out the dinosaurs when it hit the Earth 65 million years ago.

    • If an asteroid or comet of about 10 kilometers in size hit the Earth, the horrific blast could generate towering ocean waves, block out the Sunís light and heat, ignite global wildfires, drench the land and sea with acid rain, and produce deadly volcanoes on the other side of the Earth.

    • The Earth is immersed within a cosmic shooting gallery of potentially lethal, Earth-approaching asteroids that could collide with our planet and end civilization, as we know it.

    • The lifetime risk of your dying as the result of an asteroid striking the Earth is about the same as death from an airplane crash, but a lot more people would die with you during the cosmic impact.

    • It is estimated that the Earth receives a direct hit by an asteroid about two kilometers in size every million years or so, resulting in a global catastrophe. It could happen tomorrow or it might not occur for hundreds of thousands of years.

    • Astronomers are now taking a census of most of the Near-Earth Objects that are big enough and close enough to threaten us with global destruction.

    • With enough warning time, we could redirect the course of an asteroid or comet that is headed for collision with the Earth.

Copyright 2010, Professor Kenneth R. Lang, Tufts University