Bending waves in Saturn's rings

Saturn A ring brightness variations are investigated and noted to be caused by vertical corrugations of the local ring plane due to a spiral bending wave, resonantly excited by Mimas, which propagates inwardly by way of the ring particle collective gravity. Some aspects of the presently developed theory of forced bending waves have been previously treated in the galactic context. It is noted that the theory is generally in good agreement with observations, and in particular may resolve the conflict between ground-based estimates of 1-2 km for the global ring thickness and Voyager stellar occultation measurements of less than 200 m for the local ring thickness.