What's bigger than an asteroid, smaller than a planet, red all over and far, far away?

The answer -- a mysterious planet-like body orbiting our Sun -- has been discovered by NASA-funded researchers led by an astronomer at the California Institute of Technology, Pasadena, Calif.

The object is three times farther away from Earth than Pluto, making it the most distant known in the solar system.

The planetoid is usually even colder, because it approaches the Sun this closely only briefly during its 10,500 year orbit around the Sun. At its most distant, "Sedna" is 130 billion kilometers (84 billion miles) from the Sun. That is 900 times Earth's distance from the Sun.

"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 and back again. "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," said Brown.