The narrow F-Ring discovered by Pioneer 11 was found to comprise as many as five individual strands. On either side of the F-Ring, two small satellites keep the ring particles confined to their orbit by gravitational forces. These satellites are thus known as the "shepherd satellites."
The Voyager 2 image at right shows the F-Ring and its two shepherd satellites. Each satellite has a different orbital period, and the inner one passes the outer satellite every 25 days.
Individual strands of the F-Ring give it a braided appearance as seen by Voyager 1. The widest areas are clumps of ring material, and may contain tiny moons. The ring here is about 35 kilometers (25 miles) wide.