Cassini finds a Saturn moonlet

PASADENA, Calif., March 3 (UPI) -- The U.S. space agency says its Cassini spacecraft has found a moonlet within Saturn's G ring that may be a main source of the G-ring and its single ring arc.

National Aeronautics and Space Administration scientists analyzed images acquired by Cassini during the course of about 600 days and found the tiny moonlet, about one-third of a mile in diameter, embedded within a partial ring, or ring arc, previously found by Cassini in Saturn's G ring.

"Before Cassini, the G ring was the only dusty ring that was not clearly associated with a known moon, which made it odd," said Matthew Hedman, a Cassini associate at Cornell University. "The discovery of this moonlet, together with other Cassini data, should help us make sense of this previously mysterious ring."

Saturn's rings were named in the order they were discovered, scientists said. The G ring is one of the outer rings and within it there is a relatively bright 150-mile-wide arc of ring material that extends 90,000 miles, or one-sixth of the way around the ring's circumference.

The discovery brings the number of Saturnian ring arcs with embedded moonlets found by Cassini to three.

The finding was announced Tuesday in an International Astronomical Union circular.