[Follow-up from a list-member on The Odds item]

The odds for an asteroid impact are balanced by the fact that a comparatively *rare* event brings death to a very *large* number of people. By the simple laws of physics, any asteroid or comet of one kilometre or greater size travelling at 70 km per second would release enough energy on impact to create a global catastrophe. Most of the devastation would be caused not by the effect at ground zero, but by the dust thrown into the atmosphere and encircling the globe.

In 1908, a relatively *tiny* asteroid of around 60 metres in diameter collided with the Earth in Siberia flattening over 1,000 square kilometres of forest. To the best of our knowledge, there was no known loss of life; but had the same asteroid fallen on Sydney or New York, the death toll would have been different.

Even smaller asteroids (to the point where they are classified as meteoroids)

fall more frequently. What are the odds that one will fall on your head and not out in the Australian desert? Take a look at these beauties which have fallen in the Australian desert and imagine one falling on your head.

http://www.nelsonbay.com/~gc/observatory_files/page0018.htm

Hey, I’ve got to say this. I have been tracking asteroids for the last three years and feel that my efforts have been truly effective. In those three years of protecting the planet there has been no known loss of life! 😉

– Greg