The U.S. space agency's spacecraft studying Saturn has found a new moonlet in the planet's outer ring, according to a circular of the International Astronomical Union.

NASA's Cassini spacecraft found the moonlet embedded and moving within a 150-mile arc of the faint G ring. The spacecraft's camera detected the moonlet, estimated at around one-third of a mile wide, on Aug. 15, 2008.

The discovery brings to three the number of Saturnian ring arcs that have a hidden moonlet. It is also Saturn's 61st moon.

The Cassini will take a closer look at the ring arc and the new moonlet early next year.