Prometheus and Pandora • Shaping the Drapes of the F Ring • This movie sequence from Cassini shows dark drapes in the inner strands of the F ring caused by the gravitational influence of the shepherd moons Prometheus (86 kilometers, 53 miles across). Prometheus appears first in the sequence, interior to the F ring, and Pandora (81 kilometers, 50 miles across) follows along outside of the ring. Radial structure in the bright core of the ring is visible throughout the movie. The visible light imag