Prometheus: one of the Ring-Masters

Caption NASA originale:"In its own way, the shepherd moon Prometheus is one of the Master of Saturn's rings. That's because the little moon maintains the inner edge of Saturn's thin, knotted, F-Ring, while its slightly smaller cohort Pandora (84 Km across) guards the ring's outer edge.
This view is a composite of nine raw images combined in a way that improves resolution and reduces noise. The final image was magnified by a factor of five.
The image clearly shows that Prometheus is not round, but instead has an oblong, potato-like shape.
The moon was discovered during the Voyager mission, and scientists then noted ridges, valleys and craters on its surface. Hints of its varied topography are present in this view, although Cassini will likely obtain much better images of Prometheus later in the mission".