Saturn has the largest and most spectacular ring system in the solar system. Composed of swarms of ice-rock particles ranging in size from a centimeter to several meters across (and possibly even as large as a kilometer), Saturn's rings are much brighter (with an albedo of up to 0.6) than any other known rings. Though some 170,000 km wide (more if the tenuous outer portion of the E-ring is included), the rings are only about a kilometer or so thick and have a total mass of about 0.01 that of the Moon. When Earth occasionally moves through the same angle as the rings, which are slanted at 27°, they almost completely disappear from view. The rest of the time, only the outer A-ring, the brighter B-ring and the bluish inner C-ring are clearly visible through telescopes on Earth, together with several dark gaps, including the Cassini Division and the Encke Division, in which ring material is much sparser.
Four additional faint rings together with a wealth of other complex and puzzling features were discovered or confirmed by the Voyager probes. Among these features are puzzling radial inhomogeneities called spokes, first reported by amateur astronomers, that may be an effect caused by Saturn's magnetic field. The F-ring, a narrow, wavy structure just outside the A ring, is confined by two small satellites and consists of at least five individual strands with embedded knots that may be clumps of ring material or mini moons. Voyager 1 images (but not those of Voyager 2) also showed the F ring to have strange braided appearance. Complex tidal resonances exist between a number of Saturn's moons and the ring system. Some of the moons – the so-called shepherd moons, Atlas, Pandora, and Prometheus – are important in keeping the rings in place; Mimas seems to be responsible for the paucity of material in the Cassini division; while Pandora is located inside the Encke Division.
Saturn’s rings and divisions
Name
Inner radius (km)
Outer radius (km)
Width (km)
Notes
D-ring
67,000
74,500
7,500
Very tenuous. Discovered in 1969
Guerin division
C-ring (Crepe ring)
74,500
92,000
17,500
Gauzy appearance. Discovered by Bond in 1850
Lyot (Maxwell) division
87,500
88,000
500
B-ring
92,000
117,500
25,500
The brightest ring
Cassini division
115,800
120,600
4,800
Discovered by Cassini in 1675
Huygens gap
117,680
118,000
285-440
A-ring
122,200
136,800
14,600
Encke minimum
126,430
129,940
3,500
Encke division
133,580
133,910
330
F-ring
140,210
30-500
G-ring
165,800
173,800
8,000
E-ring
180,000
480,000
300,000
Saturn's rings and their shadow, imaged by the Cassini spacecraft
