Dinosaurs and asteroids

In March of 1992, three astronomers, Carolyn and Eugene Shoemaker and David Levy discovered their ninth comet, hence its name, “Shoemaker-Levy 9.” The team determined that S-L9 was orbiting Jupiter now rather than the sun. Because Jupiter is a heavy-weight planet, exerting an enormous gravitational pull, astronomers call it the solar system’s vacuum sweeper.

In July of 1992, astronomers noticed that Jupiter’s force had broken S-L9 into 23 fragments that they labelled A through W and that each were strung out in single file, like pearls on a string. Most fragments, they estimated, were little m...