Comet Shoemaker-Levy 9

Comet Shoemaker-Levy 9 (SL9, formally designated D/1993 F2) was a comet that collided with Jupiter in 1994, providing the first direct observation of the collision of two solar system objects, not including collisions involving Earth. This generated a large amount of coverage in the popular media, and SL9 was closely observed by astronomers worldwide. The comet provided many revelations about Jupiter and its atmosphere and highlighted Jupiter's role in reducing space debris in the inner solar system.

The comet was discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy. Shoemaker-Levy 9 was located on the night of March 24, 1993, in a photograph taken with the 0.4-metre Schmidt telescope at the Mount Palomar Observatory in California. It was the first comet observed while orbiting a planet rather than the Sun.

SL9 was in pieces ranging in size up to 2 kilometres in diameter, and is believed to have been pulled apart by Jupiter's tidal forces during a close encounter in July 1992. These fragments collided with Jupiter's southern hemisphere between July 16 and July 22, 1994, at a speed of approximately 60 kilometres per second (37 miles per second). The prominent scars from the impacts could be seen on Jupiter for many months after the impact, and observers described them as more easily visible than the Great Red Spot.