Asteroid rings 'totally surprising'
An asteroid orbiting the Sun between Saturn and Uranus is girdled by two rings, scientists have learned.
Previously only giant gas planets, most famously Saturn, were thought to possess rings.
The ringed space rock, called Chariklo, was originally located in the Kuiper Belt, a circling group of icy dwarf planets and comets at the edge of the Solar System.
At some point it was thrown out of the belt and now exists as the largest member of a group of objects known as the Centaurs.
Astronomers unexpectedly found the rings while using several telescopes to observe Chariklo.
"We were not even looking for rings, because they had never been observed around small objects like Chariklo, so it is a totally surprising discovery," Dr Uffe Graw Jorgensen, from teh Niels Bohr Institute at the University of Copenhagen, Denmark, said.
"We could even determine incredible details about the rings.
"There are two separate thin rings, which are comprised of ice particles and pebbles.
"The two rings are only three and seven kilometres wide and no more than a few hundred metres thick.
"There are 14 kilometres between the centres of the two rings and there is a nine kilometre wide gap between them.
"They have been measured at a distance of two billion kilometres with an accuracy of plus/minus a few hundred metres.
"It is really impressive."
The discovery is reported in the latest edition of the journal Nature.
Chariklo has a diameter of 250 kilometres.