Many of Saturn's ring structures appear to be the results of resonance with outer satellites. One prominent structure within the A-Ring is a 5:3 resonance with Saturn's moon Mimas. At this resonance, ring materials circle Saturn 5 times while Mimas orbits 3 times.
This Voyager 2, close encounter image of Saturn's A-Ring, shows two wave patterns formed from the Mimas resonance perturbations. On the left is an outward propagating spiral density wave formed by particles that are bunched together in a spiral pattern. On the right is an inward propagating spiral bending wave that is made up of vertical oscillations of the ring material. The distance between these two waves is about 400 kilometers.
Another image of these spiral waves can be found at aring3.htm.