Fast-moving planets cruise around stars (Reuters/CNN)

WASHINGTON (Reuters) -- Astronomers have discovered a possible new class of planets outside the solar system that hug their parent stars so tightly that they take less than a day to complete an orbit.

Astronomers working with the Hubble Telescope have so far identified five possible planets that orbit their parent stars in as few as 10 hours, according to a paper to be published Thursday in the scientific journal Nature.

The objects appear to be low-density gas giants similar to Jupiter, orbiting stars smaller than the sun.

About 200 planets have been discovered outside the solar system so far, including gas giants eight times closer to their parent stars than Mercury is to the sun.
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more: http://www.cnn.com/2006/TECH/space/10/04/space.planets.reut/index.html