Portal:Astronomy/Featured/December 2005

Comet Shoemaker-Levy 9 (formally designated D/1993 F2) was discovered in a photograph taken on the night of March 24, 1993 with the 0.4-metre Schmidt telescope at the Mount Palomar Observatory in California, and was the ninth comet discovered by astronomers Carolyn and Eugene M. Shoemaker and David Levy. It turned out to be the first comet observed orbiting a planet (Jupiter, in this case) and not the Sun. The comet was also unusual because it was in fragments (ranging in size up to 2 kilometres in diameter), due to a close encounter with Jupiter in July 1992 when it approached closer to the planet than its Roche limit and was pulled apart by tidal forces.

Between July 16 and July 22, 1994, the fragments of the comet collided with Jupiter's southern hemisphere at 60 kilometres per second (37 miles per second), providing the first direct observation of the collision of two Solar System objects. The collision resulted in disruptions in Jupiter's atmosphere, such as plumes and bubbles of gas, and dark spots in the atmosphere which remained visible for several months.

The event was closely observed and recorded by astronomers worldwide as a result of its tremendous scientific importance, and also generated a large amount of coverage in the popular media. The event highlighted Jupiter's role in reducing the amount of space debris in the inner Solar System, which is thought to be a prerequisite for unbroken development of life.

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