[meteorite-list] Most Distant Object In Solar System Discovered

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:32:50 2004
Message-ID: <200403151825.KAA12356_at_zagami.jpl.nasa.gov>

MEDIA RELATIONS OFFICE
JET PROPULSION LABORATORY
CALIFORNIA INSTITUTE OF TECHNOLOGY
NATIONAL AERONAUTICS AND SPACE ADMINISTRATION
PASADENA, CALIF. 91109 TELEPHONE (818) 354-5011
http://www.jpl.nasa.gov

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

Donald Savage/Dwayne Brown (202) 358-1547/1726
NASA Headquarters, Washington

NEWS RELEASE: 2004-085 March 15, 2004

Most Distant Object In Solar System Discovered

NASA-funded researchers have discovered the most distant object
orbiting Earth's Sun. The object is a mysterious planet-like body
three times farther from Earth than Pluto.

"The Sun appears so small from that distance that you could completely
block it out with the head of a pin," said Dr. Mike Brown, California
Institute of Technology, Pasadena, Calif., associate professor of
planetary astronomy and leader of the research team. The object,
called "Sedna" for the Inuit goddess of the ocean, is 13 billion
kilometers (8 billion miles) away, in the farthest reaches of the
solar system.

This is likely the first detection of the long-hypothesized "Oort
cloud," a faraway repository of small icy bodies that supplies the
comets that streak by Earth. Other notable features of Sedna include
its size and reddish color. After Mars, it is the second reddest
object in the solar system. It is estimated Sedna is approximately
three-fourths the size of Pluto. Sedna is likely the largest object
found in the solar system since Pluto was discovered in 1930.

Brown, along with Drs. Chad Trujillo of the Gemini Observatory,
Hawaii, and David Rabinowitz of Yale University, New Haven, Conn.,
found the planet-like object, or planetoid, on Nov. 14, 2003. The
researchers used the 48-inch Samuel Oschin Telescope at Caltech's
Palomar Observatory near San Diego. Within days, telescopes in Chile,
Spain, Arizona and Hawaii observed the object. NASA's new Spitzer
Space Telescope also looked for it.

Sedna is extremely far from the Sun, in the coldest know region of our
solar system, where temperatures never rise above minus 240 degrees
Celsius (minus 400 degrees Fahrenheit). The planetoid is usually even
colder, because it approaches the Sun only briefly during its
10,500-year solar orbit. At its most distant, Sedna is 130 billion
kilometers (84 billion miles) from the Sun, which is 900 times Earth's
solar distance.

Scientists used the fact that even the Spitzer telescope was unable to
detect the heat of the extremely distant, cold object to determine it
must be less than 1,700 kilometers (about 1,000 miles) in diameter,
which is smaller than Pluto. By combining available data, Brown
estimated Sedna's size at about halfway between Pluto and Quaoar, the
planetoid discovered by the same team in 2002.

The elliptical orbit of Sedna is unlike anything previously seen by
astronomers. However, it resembles that of objects predicted to lie in
the hypothetical Oort cloud. The cloud is thought to explain the
existence of certain comets. It is believed to surround the Sun and
extend outward halfway to the star closest to the Sun. But Sedna is 10
times closer than the predicted distance of the Oort cloud. Brown said
this "inner Oort cloud" may have been formed by gravity from a rogue
star near the Sun in the solar system's early days.

"The star would have been close enough to be brighter than the full
moon, and it would have been visible in the daytime sky for 20,000
years," Brown explained. Worse, it would have dislodged comets farther
out in the Oort cloud, leading to an intense comet shower that could
have wiped out some or all forms of life that existed on Earth at the
time.

Rabinowitz said there is indirect evidence that Sedna may have a moon.
The researchers hope to check this possibility with NASA's Hubble
Space Telescope. Trujillo has begun to examine the object's surface
with one of the world's largest optical/infrared telescopes, the
8-meter (26-foot) Frederick C. Gillett Gemini Telescope on Mauna Kea,
Hawaii. "We still don't understand what is on the surface of this
body. It is nothing like what we would have predicted or what we can
explain," he said.

Sedna will become closer and brighter over the next 72 years, before
it begins its 10,500-year trip to the far reaches of the solar system.
"The last time Sedna was this close to the Sun, Earth was just coming
out of the last ice age. The next time it comes back, the world might
again be a completely different place," Brown said.

NASA's Jet Propulsion Laboratory, Pasadena, Calif, manages the Spitzer
Space Telescope. For more information about the research and images on
the Internet, visit

http://www.spitzer.caltech.edu/Media/releases/ssc2004-05/

For information about NASA on the Internet, visit

http://www.nasa.gov

-end-
Received on Mon 15 Mar 2004 01:24:54 PM PST