Gravitational Anomalies and Interferences in the Rings

Caption NASA originale:"Image A displays an unusual mottled-looking narrow region, with a radial width varying with longitude from 5 to 10 Km, seen for the first time about 60 Km inside the outer edge of Saturn's A-Ring.
Image B is a close-up of this region, mapped into a longitude-radius system and contrast enhanced, that is characterized by blotchy light and dark areas about 30/40 Km in longitudinal extent.
The mottled regions also are probably caused by particle clumping brought about by gravitational disturbances. The outer A-Ring edge is sculpted into a 7-lobed pattern called a Lindblad resonance (a type of dynamical resonance that occurs in rings systems) with the co-orbital satellites Janus and Epimetheus. The resonant perturbations in this region are complicated by the presence of these 2 moons whose orbits are within 50 Km of each other.
Image C is a dark-side image of the outer edge of the Encke gap, with a resolution of about 270 meters per pixel".