Pandora

Pandora lives beside one of Saturn's most restless structures. It circles just outside the narrow F ring, close enough for the moon and the ring to continually affect one another. Voyager 1 discovered Pandora in 1980, but Cassini turned it from a small point near the rings into a visibly irregular world.

Cassini's close views revealed a surface mantled in fine icy debris. Many craters look shallow because material has softened or partly filled their outlines, while ridges and grooves cross the small moon beneath the dust. Pandora is therefore not simply a bare chunk of ice: its appearance records an ongoing exchange with the ring environment around it.

Pandora was once commonly described as the F ring's outer shepherd, paired neatly with Prometheus on the inside. The modern picture is less symmetrical. Prometheus does most of the work of confining the ring's narrow core, while Pandora tends to disturb it. That makes Pandora valuable precisely because it replaces a tidy textbook image with a more dynamic one: a moon beside a ring whose structure is continually being reshaped.