The Cassini spacecraft has detected what appears to be a large debris disk around Saturn's 1520 kilometer wide moon Rhea. If confirmed, it would be the first ring system ever found around a moon.
Scientists believe that the halo probably contains particles ranging from the size of grains to boulders. It's not certain how the rings have originated. One explanation may be that they came from an ancient asteroid/comet collision, which spattered material around Rhea.
The finding was described in a study published in the March 7 issue of the journal Science.