The structures in the outer edge of Saturn's most massive ring, the B ring, appear to be oscillating in at least three rotating wave patterns. This may be helping to create the complex variation seen in the ring's behaviour.
Until recently, researchers thought that the region was dominated solely by the gravitational influence of Saturn's moon Mimas. Joseph Spitale and Carolyn Porco of the Space Science Institute in Boulder, Colorado, pored over thousands of images of the B ring region (pictured) taken by NASA's Cassini spacecraft during its initial four-year exploration of the planet. The duo discovered the wave patterns, which arise spontaneously owing partly to the high density in the ring. They also found evidence for the existence of small moons trapped in the region.
The findings offer insight into similar oscillations in other astronomical systems, such as spiral galaxies, and protoplanetary disks orbiting nearby stars.