Houston: US astronomers have found an icy, red planet-like object, orbiting the sun eight billion miles away, twice as far as Pluto, and stretching the limits of the solar system beyond anything discovered so far.

Space officials announced the discovery at National Aeronautics and Space Administration's (NASA) Jet Propulsion Laboratory in Pasadena, California yesterday (Mar 15, 2004). Researchers discovered the object in November 2003.

Scientists said the object may be the first visible evidence of the 'Oort Cloud', a massive spherical shell of comets thought to be loosely orbiting the sun and extending outward almost halfway to the nearest star.

"There's absolutely nothing else like it known in the solar system," said Michael Brown of the California Institute of Technology in Pasadena.

The object is catalogued as 2003 VB12 and has unofficially been dubbed 'Sedna', Goddess of the sea for Arctic dwellers. Brown thought that appropriate given the frigid conditions under which the solar system body has probably always existed. The International Astronomical Union would have to approve the name.

It may even have its own little moon.

Sedna is estimated to be 2,000-kilometre in diameter and is about 90 per cent the size of Pluto's, making it the largest Solar System object discovered since Pluto itself in 1930.

Researchers at the California Institute of Technology discovered the planet using the new Spitzer space telescope, which made its debut last August.