Comet Shoemaker-Levy 9 is so-named because it was the ninth short-period comet discovered by Carolyn and Eugene Shoemaker and David Levy. It was first detected in a photograph taken on the night of March 24, 1993 with the 0.4-meter Schmidt telescope at the Mount Palomar observatory in California, and subsequently observed by many other astronomers. The comet was extremely unusual because it was in fragments, evidently due to a close encounter with the planet Jupiter in July 1992. It is thought to have been pulled apart by tidal forces.
During the period July 16-July 22 1994, over twenty fragments of the comet collided with Jupiter's southern hemisphere, providing the first direct observation of the collision of two solar system objects. The event was closely observed and recorded by astronomers worldwide, because of its tremendous scientific importance.