Far out.

How big is our solar system? Astronomers are hoping that a newly discovered "planetoid" will hold a clue.

The discovery of Sedna, which is three times as far from the sun as Pluto, the solar system's most distant planet, has raised many questions. What is Sedna made of? What makes it glow red? Can we call it a planet? Sedna is smaller than Pluto, which some astronomers say is too small to be considered a planet.

"There's absolutely nothing else like it known in the solar system," said astronomer Michael Brown, whose team at the California Institute of Technology's Palomar Observatory first observed Sedna. "Our prediction is that there will be many, many more of these objects discovered in the next five years, and some of them will probably be more massive."

The California team estimates that Sedna requires 10,500 Earth years to complete a single 84-billion-rnile orbit around the sun. "The last time Sedna was this close to the sun," Brown said, "Earth was just coming out of the last ice age."

The temporary name for the frigid planetoid is 2003 VB12, but Brown would like to call it Sedna, after an Inuit sea goddess. The Inuit live in the Arctic region, one of the coldest places on Earth.