Giant planet Saturn has many millions of tiny moons orbiting it, astronomers have discovered.
They make up the spectacular system of rings that encircle the solar system’s second biggest world.
Scientists had wondered if the brilliant rings, which can be seen in small telescopes, formed from the disk of material that created Saturn itself.
But the new evidence, from the spacecraft Cassini, which took the picture, above right, points to them being produced by the break-up of a larger body such as a full-sized moon.
Saturn, which is 75,000 miles wide and big enough to contain 763 Earths, has a system made up of countless rings.
Just one alone could be made up of as many as ten million moonlets, say scientists in a report in this week’s journal Nature.
Saturn already has 47 confirmed moons in orbit around it. The biggest, Titan, is the second largest in the solar system.
Joseph Burns, one of the report’s authors, of Cornell University, New York, said: “”These moonlets are likely to be chunks of the ancient body whose break-up produced Saturn’s glorious rings.”
Previous measurements from Nasa’s Voyager spacecraft in the early 1980s showed that Saturn’s rings contain mostly small particles of water-ice.
The latest findings allso help astronomers to determine the true nature of two of Saturns’s smaller moons, Pan and Daphnis.
Co-author Matthew Tiscareno, also of Cornell, said: “The discovery of these intermediate-sized bodies tells us that Pan and Daphnis are probably just the largest members of the ring population, rather than interlopers from somewhere else.”
Another author of the report is Carl Murray, a member of the Cassini team at Queen Mary, University of London. He said: “Cassini is giving us a unique insight into the origin of planets.”
© Paul Sutherland. Unauthorised reproduction forbidden.