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Comets 101: A primer on the 'dirty snowballs' of space

By: Katherine Butler on Jan. 11, 2012, 10:35 a.m.
Comet 17P/Holmes

Photo: NASA/JPL/Cal-Tech

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Anatomy of a busted comet

Like most objects in space, comets retain some mystery. Pictured here is the Comet 17P/Holmes. This comet is thought to travel between Jupiter and the sun “without incident” every six years. Recently, it added some illumination to its trip when it suddenly brightened in midroute to the sun. According to NASA, “twice in the last 116 years, in November 1892 and October 2007, Comet Holmes mysteriously exploded as it approached the asteroid belt.” There are thought to be as many as 3,572 comets travelling around our solar system.