This is an artist's concept of Saturn's rings and major icy moons.
Saturn's rings make up an enormous, complex structure. From edge-to-edge,
the ring system would not even fit in the distance between Earth and the
Moon. The seven main rings are labeled in the order in which they were
discovered. From the planet outward, they are D, C, B, A, F, G and E.
The D ring is very faint and closest to Saturn. The main rings are A, B
and C. The outermost ring, easily seen with Earth-based telescopes, is the
A ring. The Cassini Division is the largest gap in the rings and separates
the B ring from the A ring. Just outside the A ring is the narrow F ring,
shepherded by tiny moons, Pandora and Prometheus. Beyond that are two much
fainter rings named G and E. Saturn's diffuse E ring is the largest
planetary ring in our solar system, extending from Mimas' orbit to Titan's
orbit, about 1 million kilometers (621,370 miles).
The particles in Saturn's rings are composed primarily of water ice and
range in size from microns to tens of meters. The rings show a tremendous
amount of structure on all scales; some of this structure is related to
gravitational interactions with Saturn's many moons, but much of it
remains unexplained. One moonlet, Pan, actually orbits inside the A ring
in a 330-kilometer-wide (200-mile) gap called the Encke Gap. The main
rings (A, B and C) are less than 100 meters (300 feet) thick in most
places, compared to their radial extent of 62,120 kilometers (38,600
miles). The main rings are much younger than the age of the solar system,
perhaps only a few hundred million years old. They may have formed from
the breakup of one of Saturn's moons or from a comet or meteor that was
torn apart by Saturn's gravity.
The Cassini-Huygens mission is a cooperative project of NASA, the European
Space Agency and the Italian Space Agency. The Jet Propulsion Laboratory,
a division of the California Institute of Technology in Pasadena, manages
the mission for NASA's Science Mission Directorate, Washington, D.C. The
Cassini orbiter was designed, developed and assembled at JPL.
For more information about the Cassini-Huygens mission visit
http://www.nasa.gov/cassini and http://saturn.jpl.nasa.gov.