Fomalhaut's Planet

StarDate: October 25, 2009

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The roster of known planets in other solar systems is getting close to 400. Almost all of these planets were discovered indirectly -- usually through their gravitational pull on their parent stars. But at least one planet was discovered directly. Astronomers found it in pictures snapped by Hubble Space Telescope.

The planet orbits Fomalhaut, a bright star that's low in the southeast as night falls, to the lower left of brilliant Jupiter.

Fomalhaut is fairly young -- only a few percent as old as the Sun. It's still surrounded by a broad disk of gas and dust left over from its birth -- the raw materials for planets.

Astronomers first saw the disk in a 2004 snapshot from Hubble. The picture revealed a small, bright blob in the outer regions of the disk. It's more than 10 billion miles from Fomalhaut -- about four times the distance between the Sun and Neptune, the most-distant planet in our own solar system.

Another snapshot in 2006 showed that the blob was still there, but it had moved a tiny bit around Fomalhaut. Astronomers realized that they'd seen a planet -- one of the first planets ever photographed, and the first actually discovered through images.

The planet is up to three times the mass of Jupiter, the giant of our own solar system. And it's probably surrounded by its own disk of material. The disk may be giving birth to moons -- just as the disk around Fomalhaut gave birth to this giant planet.

Script by Damond Benningfield, Copyright 2009

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