Rings Home

Saturn’s rings were formed about 100 million years ago, which is approximately 2% of the age of the solar system.

There age currently three theories as to how the rings around Saturn formed. The first suggests that material leftover from the formation of the solar system gathered around Saturn. However, because that material was within the Roche limit, it did not form satellites. The second theory suggests that a medium sized moon drifted within the Roche limit of Saturn, where it was torn apart by the tidal forces of Saturn. The third theory suggests that it is the remnant of a moon that was shattered to pieces by meteor impacts.

The rings of Saturn are consist of icy moonlets. These icy moonlets are composed of objects as small as dust particles to objects the size of icebergs, or even larger. However, most of the objects that make up the rings are in the range of one to five centimeters. The surface of the icy moonlets is generally water, however, some impurities have been found.

There are seven major groupings of rings around Saturn, designated letters "A" through "G." The D-ring is the closest to Saturn, followed by the C-ring, the B-ring, the A-ring, the F-ring, the G-ring, and the E-ring (see chart below).

*Measured from the centre of Saturn to the innermost edge of the ring

While the rings are over 250,000 km in diameter, they are at the very most, 1.5 km thick. Generally, the rings are between 10 and 100 meters thick. However, despite this large diameter, most the rings are empty space. If the rings were compacted into a single body, they would be no more than 100 km across.

There are over a thousand individual rings around Saturn; however, these are grouped into seven main rings. Of these seven rings, the A and B-rings are the predominant ones, followed by the C-ring. There is a large gap between the A and B-rings, called the Cassini division. This was named after Jean Cassini, the discoverer of the gap. The gap is about 4800 km wide; however, this changes throughout its length. There is a much smaller gap beyond the A-ring, called the Encke Gap; however, this was likely never seen by Encke. There are lesser gaps throughout the rings of Saturn, however, they are not as important as the Cassini and Encke Gaps. The gaps throughout the rings are caused by the gravitational pull of the satellites on the particles of the rings. The satellites responsible for this are called "shepherding satellites."

The outermost ring of Saturn is the F-ring. This ring is an intricate structure made up of smaller rings along which "knots" are found. These "knots" are believed to be clumps of ring material or possible mini moons.

The rings are moving around Saturn, and complete one revolution about every 10 hours. The particles closer to the planet, however, move at a greater velocity than those in the outer parts of the rings.