The lighting geometry in this image is extreme. It was taken just hours before equinox, mostly of the C ring, one of the dimmest of Saturn's main rings. The B ring's inner boundary is on the right; the C ring's Maxwell gap (demarcated by two bright arcs, which are bright because they rise above the ring plane) is on the left. There is a periodic brightness variation in the image. The side lighting geometry means that brightness variations mostly result from changing slopes of the surface of the ring plane due to out-of-plane disturbances in the rings -- in layman's terms, the rings here are corrugated like a washboard. Previous images had revealed these corrugations in the D ring (located off the view to the left). This image reveals that the corrugation extends beyond their origin in the D ring (which begins not far above Saturn's cloud tops), right through the C ring, to the inner part of the B ring, the densest of Saturn's rings, covering a distance of 17,000 kilometers. This was a wholly unexpected observation.