In July of 1994, an astounding series of events took place. The world anxiously
watched as, every few hours, a hurtling chunk of comet plunged into the atmosphere of
Jupiter. All of the twenty-odd fragments, collectively called comet 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 cometary 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, producing 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 commonplace, at least in
geologic terms, and were even more frequent in the early solar system.
3. The author compares the fragments of comet Shoemaker-Levy 9 to all of the following EXCEPT
(A) a dismembered body
(B) a train
(C) a pearl necklace
(D) a giant planet
答案:D