Among Saturn's shimmering ice belts, the planet's G ring has proved the most puzzling. The very location of this faint, narrow ring, well beyond the planet's main ring system, has been a riddle ever since the two Voyager spacecraft spied it in 1980. The G ring lies more than 15,000 kilometers from any Saturnian moon. It's neither flanked by bodies that might corral its particles, as the moons Pandora and Prometheus do for the F ring, nor close to an object that could shed particles to populate the ring, as Enceladus does for the E ring.
Now, in one fell swoop, the Saturn-touring Cassini spacecraft has discovered the source of the G ring and identified the body whose gravit