Astronomers have discovered a strange new world in the solar system, they revealed today – and they have nicknamed it Buffy.
The object first showed up in observations made last December from Hawaii.
Since October this year, the scientists have been monitoring its movement using a giant telescope on the island.
They believe Buffy – which is still officially known only as XR190 – is up to 600 miles in diameter, half as wide as Pluto which is officially the ninth planet.
It lies 58 times further away from the sun than the Earth, beyond the orbit of the eighth planet Neptune.
Other giant bodies have also been found beyond Neptune, including one which astronomers called Xena after the warrior princess.
Unlike the classical planets, which all lie on roughly the same level and all travel through the zodiac, Buffy has a very steep tilt of 47° to it.
It may have been thrown out of orbit when it passed close to another body travelling through space.
The astronomers, led by Lynne Allen of the University of British Columbia, Vancouver, Canada, believe Buffy is one of a vast number of undiscovered icy words beyond Neptune in a ring called the Kuiper Belt.