COOL FACTS

How can a particle the size of a grain of sand produce such a spectacular sight? The answer is the speed at which the meteoroid enters the earth's atmosphere. Many meteoroids travel at 60-70 kilometers per second. As a comparison, the space shuttle moves around the earth at about 8 kilometers per second.

Early in the history of the solar system, after the formation of the planets and their moons, there was still a lot of smaller objects in inter-planetary space. Over time many of these objects collided with the earth and moon. Because the moon has no atmosphere and is not geologically active, the craters are still visible. On earth, however, the workings of the atmosphere, water, and continental movements have hidden most craters. Over 150 impacts have been studied on the earth, though the true number will never be known.