Astronomers discover frozen world
By Gwyneth K. Shaw
The Orlando Sentinel

Washington - A shiny red "planetoid" locked in a bizarre orbit may be the most distant object orbiting our sun, astronomers announced Monday.

In its 10,500 - year orbit, the lump of what is probably rock and ice never gets closer to the sun than 8 billion miles. And at its farthest point, the mass is an astonishing 84 billion miles away.

"There is absolutely nothing else like it known in the the solar system," said Michael Brown, an astronomer at the California Institute of Technology. Unofficially dubbed Sedna - after t he Inuit goddess of the sea - the object is between 800 and 1,100 miles in diameter, around half the size of Earth's moon. It is likely the largest thing seen orbiting the sun since the discovery of Pluto in 1930, and the questions it raises have astronomers both baffled and excited.

"Very little happened to this object since the beginning of the solar system," Brown said. "It really has just been sitting out there at 400 degrees below zero."

Brown hypothesized that Sedna may be made of rock and ice, but said it is really impossible to know.

What Brown and two others NASA - funded, is that Sedna is in a highly orbit - a long ellipse that, at its furthest, is more than 900 times as far from the sun as Earth.

The average distance between Earth and the sun is about 93 million miles.

In the evening sky, looking west-southwest, Sedna is about halfway between the planet Venus and the constellation Orion, Brown said. But because of its great distance, the planetoid is too faint for most amateur astronomers to see.

Sedna is so far away from the sun, Brown said, that if you were standing on its surface, you could obscure the sun with the head of a pin held at arm's length.

Brown and his colleagues, Chad Trujillo of the Gemini Observatory in Hawaii and Yale University's David Rabinowitz, discovered the object in November, using a telescope with a 48-inch lens at Caltech's Palomar Observatory near San Diego, as part of a long-term survey.

The scientists knew they were on to something because in three images from the telescope, they could see one thing moving slowly across the sky - a clear indication of something within our solar system.

Sedna is, but it is at the very outer edge. It is well beyond Pluto, and even outside the Kuiper Belt, a band of icy debris at the fringe of the solar system. Its size places it between Pluto and the smaller Quaoar, another object discovered by Brown and Trujillo in 2002.

Valley Morning Star 3-16-04