PASADENA, Calif., July 9 (UPI) -- Observations by the Cassini spacecraft have shown Saturn's rings are a lot dirtier than originally thought, NASA officials said Friday.
The new observations show the inner regions of the rings are packed with rock and mud.
"We've known for decades the rings are mostly made of water," said Larry Esposito of the University of Colorado at Boulder. "Now we know the amount of water varies, increasing toward the outer edge of the rings.
Mission scientists combined Cassini images made in ultraviolet light with infrared pictures taken during the June 30 pass through the ring plane -- at a place called the Cassini gap, named for the Italian astronomer who discovered them.
No one knows how the rings formed. One idea is that an icy object from the outer solar system was lured in close and broken apart by Saturn's massive gravity. The new data are not conclusive, but they can be read to support that theory, mission scientists said.
The rings' composition remains unknown, but based on the observations, scientists think it is silicates and organic material -- the same kind of material that comprises rocks and dirt on Earth. The ice is also thought to contain water mixed with other frozen substances such as ammonia.
