Around the Track

Shepherd moons Prometheus and Daphnis race around Saturn’s rings within their respective gaps, affecting the ring material in their own distinct ways. Prometheus, on the left side, pulls the bright, ropy F ring into streamers while tiny Daphnis, embedded in the 25-mile-wide Keeler gap at lower center, sends up a mound of darker A ring…

Shepherds Fly

  Two of Saturn’s smaller moons pass by Cassini’s wide-angle camera in this animation sequence, made from 60 raw images taken on May 26, 2009. Prometheus enters first, stage right, deforming the ringlets of the F ring with its gravity, and is followed shortly after by Atlas, taking the inside track around the edge of…