Death of the Dinosaurs

Abstract

If a small comet or asteroid should strike the Earth tomorrow, the damage could be very great or relatively small, depending on where the projectile struck. There still remain unpopulated areas of our planet, and the explosive formation of even a 5-mile-wide crater in such a place (Western Australia, the Gobi Desert, the Sahara, or even central Nevada) would not dramatically affect most of the people in the world. On the other hand, such an impact in a heavily populated urban region would kill millions of people, dwarfing the effects of the Hiroshima or Nagasaki atom bomb. But what of still larger projectiles? At what point would the catastrophe become truly global, regardless of the exact point of impact? Our planet is a big place, but worldwide catastrophes caused by collisions are by no means impossible.