In hopes of being the first geologist on the moon, Eugene Shoemaker became an expert in impact craters. After studying craters produced by atomic bomb tests, Gene realized, contrary to current geological thought, that the Earth has been bombarded in the past by large objects from space. These impacts produced huge craters such as the ones in Arizona and the Ries Basin in Germany. After being rejected by the astronaut program for medical reasons, he and his wife Carolyn started a telescope search for near-Earth objects that could pose a collision threat. Working with astronomer David Levy, they found quite a few comets and asteroids, including the famous comet Shoemaker-Levy-9 which collided with Jupiter. Could Earth be next in this cosmic shooting-gallery? And what could we do about it, if anything?