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The Tenth Planet

August 2005

Discovery Image
Motion through the Stars
Size
The Kuiper Belt

Sources:

NASA
Sky & Telescope

Looking towards the Sun fron the Kuiper Belt. 2003UB313 is shown in the foreground. Artist's Concept, NASA

The new planet, 2003UB313, is a Kuiper Belt object. The Kuiper Belt is a dark realm beyond Neptune containing thousands of small icy bodies orbiting the Sun in the plane of the Solar System.

The Kuiper Belt was hypothesised by Kuiper in the 1950s as the source of short period comets. The first Kuiper Belt objects were discovered by David Jewitt and Jane Luu in the 1990s. Hundreds have now been detected. The new planet appears to be a typical, icy Kuiper Belt object. It is the largest object in the Kuiper belt so far discovered.