This image from the NASA/ESA/ASI Cassini-Huygens spacecraft shows variations in ring particle concentration, giving Saturn's rings the appearance of ripples on a pond.
This close-up view was taken with the Cassini narrow-angle camera on 29 October 2004, at a distance of approximately 824 000 kilometres from Saturn.
Many of the gaps and wavelike patterns elsewhere in the rings are due to the gravitational influence of Saturn's moons, but the origin of much of the structure in the B ring seen here is still unexplained.
The Cassini-Huygens mission is a co-operative project of NASA, ESA and ASI, the Italian space agency.
Credit: NASA/JPL/Space Science Institute