Prometheus: the "Ring-Shaper"...

Caption NASA originale:"Prometheus zooms across the Cassini spacecraft's field of view, attended by faint streamers and deep gores in Saturn's F-Ring. This frame (taken from a movie sequence of five images) shows the F-Ring shepherd moon shaping the Ring's inner edge.
Note (watching the movie) that the faint ringlet coincident with the orbit of Prometheus (only 102 Km or approx. 63 miles across) decreases sharply in brightness behind the moon in its path. The normally twisted-looking F-Ring core is overexposed in the images, causing its appearance to be more uniform than it usually is.

This image was taken in visible light with the Cassini spacecraft narrow-angle camera on Aug. 11, 2006, at a distance of approx. 2,2 MKM (about 1,4 MMs) from Saturn and at a Sun-Saturn-spacecraft, or phase, angle of 162°. Image scale is roughly 13 Km (about 8 miles) per pixel".