NASA scientists discover tenth planet

Dolores Beasley
Headquarters, Washington July 29, 2005
(Phone: 202/358-1753)

Jane Platt
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/354-0880)

RELEASE: 05-209

NASA SCIENTISTS DISCOVER TENTH PLANET

A planet larger than Pluto has been discovered in the outlying regions
of the solar system.

The planet was discovered using the Samuel Oschin Telescope at Palomar
Observatory near San Diego, Calif. The discovery was announced today by
planetary scientist Dr. Mike Brown of the California Institute of Technology
in Pasadena, Calif., whose research is partly funded by NASA.

The planet is a typical member of the Kuiper belt, but its sheer size in
relation to the nine known planets means that it can only be classified as a
planet, Brown said. Currently about 97 times further from the sun than the
Earth, the planet is the farthest-known object in the solar system, and the
third brightest of the Kuiper belt objects.

"It will be visible with a telescope over the next six months and is
currently almost directly overhead in the early-morning eastern sky, in the
constellation Cetus," said Brown, who made the discovery with colleagues
Chad Trujillo, of the Gemini Observatory in Mauna Kea, Hawaii, and David
Rabinowitz, of Yale University, New Haven, Conn., on January 8.

Brown, Trujillo and Rabinowitz first photographed the new planet with the
48-inch Samuel Oschin Telescope on October 31, 2003. However, the object was
so far away that its motion was not detected until they reanalyzed the data
in January of this year. In the last seven months, the scientists have been
studying the planet to better estimate its size and its motions.

"It's definitely bigger than Pluto," said Brown, who is a professor of
planetary astronomy.

Scientists can infer the size of a solar system object by its brightness,
just as one can infer the size of a faraway light bulb if one knows its
wattage. The reflectance of the planet is not yet known. Scientists can not
yet tell how much light from the sun is reflected away, but the amount of
light the planet reflects puts a lower limit on its size.

"Even if it reflected 100 percent of the light reaching it, it would still
be as big as Pluto," says Brown. "I'd say it's probably one and a half times
the size of Pluto, but we're not sure yet of the final size.

"We are 100 percent confident that this is the first object bigger than
Pluto ever found in the outer solar system," Brown added.

The size of the planet is limited by observations using NASA's Spitzer Space
Telescope, which has already proved its mettle in studying the heat of dim,
faint, faraway objects such as the Kuiper-belt bodies. Because Spitzer is
unable to detect the new planet, the overall diameter must be less than
2,000 miles, said Brown.

A name for the new planet has been proposed by the discoverers to the
International Astronomical Union, and they are awaiting the decision of this
body before announcing the name.

For more information see:

http://www.gps.caltech.edu/~mbrown

For information about NASA and agency programs on the Web, visit:

http://www.nasa.gov/home/index


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Jacques :-)

www.spacepatches.info