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  Comet Shoemaker-Levy 9
 | Collisions 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 Jupiter’s 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.
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