Comet Shoemaker-Levy 9
As comets come into the Solar
System from the Oort Cloud or the Kuiper Belt, they cross the orbits
of the planets. Once in a while, a planet and a comet collide.
We recently witnessed the results of one such event: the collision of
Comet Shoemaker-Levy 9 with Jupiter. This comet was found in 1993 by
the team of Gene and Carolyn Shoemaker and David Levy. While it
appeared as a streak on the first photographs, later pictures revealed
that the comet was broken into 20 pieces, probably by coming too close
to Jupiter in the past. In July of 1994, all of the pieces of
Shoemaker-Levy 9 hit Jupiter. The impacts caused explosive
plumes of gas to shoot many thousands of kilometers into space above
Jupiter. Large dark "scars" the size of the Earth also
appeared in Jupiterís atmosphere. Many of them were still visible
month later. As of 1999, small bits of debris thrown up by the impact
continue to hit the planet.