In July of 1994, an astounding series of events took place. The world anxiously
　　
　　watched as, every few hours, a hurtling chunk of #et plunged into the atmosphere of
　　
　　Jupiter. All of the twenty-odd fragments, collectively called #et Shoemaker-Levy 9
　　
　　Line after its discoverers, were once part of the same object, now dismembered and strung out
　　
　　(5)  along the same orbit. This #etary train, glistening like a string of pearls, had been first
　　
　　glimpsed only a few months before its fateful impact with Jupiter, and rather quickly
　　
　　scientists had predicted that the fragments were on a collision course with the giant
　　
　　planet. The impact caused an explosion clearly visible from Earth, a bright flaming fire
　　
　　that quickly expanded as each icy mass incinerated itself. When each fragment slammed
　　
　　(10) at 60 kilometers per second into the dense atmosphere, its immense kinetic energy was
　　
　　transformed into heat, p

roducing a superheated fireball that was ejected back through the
　　
　　tunnel the fragment had made a few seconds earlier. The residues form these explo-
　　
　　sions left huge black marks on the face of Jupiter, some of which have stretched out to
　　
　　from dark ribbons.
　　
　　(15)  Although this impact event was of considerable scientific importance, it especially piqued
　　
　　public curiosity and interest. Photographs of each collision made the evening television
　　
　　newscast and were posted on the Internet. This was possibly the most open scientific
　　
　　endeavor in history. The face of the largest planet in the solar system was changed before
　　
　　our very eyes. And for the very first time, most of humanity came to fully appreciate the
　　
　　(20) fact that we ourselves live on a similar target, a world subject to catstrophe by random
　　
　　assaults from celestial bodies. That realization was a surprise to many, but it should not
　　
　　have been. One of the great truths revealed by the last few decades of planetary explo-
　　
　　ration is that collisions between bodies of all sizes are relatively #monplace, at least in
　　
　　geologic terms, and were even more frequent in the early solar system.