Planetary rings that are considerably fainter or discontinuous along part of their length. The F Ring of Saturn, a very thin ring outside the A Ring discovered by the Voyager probes, has brighter areas within it. Ring arcs were also suspected to exist around Neptune as a result of ground-based observations of stellar occultations. Voyager 2 found that most of the matter in Neptune’s outer ring (the Adams Ring) was concentrated in four bright arcs now named Liberté, Égalité, Fraternité, and Courage.