Montage of Saturn and several of its satellites, Dione, Tethys, Mimas, Enceladus, Rhea, and Titan.
Saturn and its satellites
Saturn has 18 officially recognized and named satellites. In addition, there are other unconfirmed satellites. One circles in the
orbit of Dione, a second is located between the orbits of Tethys and Dione, and a third is located between Dione and Rhea.
The unconfirmed satellites were found in Voyager photographs, but were not confirmed by more than one sighting. Recently,
the Hubble Space Telescope imaged four objects that might be new moons.
Several generalizations can be made about the satellites of Saturn. Only Titan has an appreciable atmosphere. Most of the
satellites have a synchronous rotation. The exceptions are Hyperion, which has a chaotic orbit, and Phoebe. Saturn has a
regular system of satellites. That is, the satellites have nearly circular orbits and lie in the equatorial plane. The two exceptions
are Iapetus and Phoebe. All of the satellites have a density of < 2 gm/cm3. This indicates they are composed of 30 to 40%
rock and 60 to 70% water ice. Most of the satellites reflect 60 to 90% of the light that strikes them. The outer four satellites
reflect less than this and Phoebe reflects only 2% of the light that strikes it.
The following table summarizes the radius, mass, distance from the planet center, discoverer and the date of discovery of each
of the confirmed satellites of Saturn:
Radius Mass Distance
Moon # (km) (kg) (km) Discoverer Date
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Pan XVIII 9.655 ? 133,583 M. Showalter 1990
Atlas XV 20x15 ? 137,640 R. Terrile 1980
Prometheus XVI 72.5x42.5x32.5 2.7e+17 139,350 S. Collins 1980
Pandora XVII 57x42x31 2.2e+17 141,700 S. Collins 1980
Epimetheus XI 72x54x49 5.6e+17 151,422 R. Walker 1966
Janus X 98x96x75 2.01e+18 151,472 A. Dollfus 1966
Mimas I 196 3.80e+19 185,520 W. Herschel 1789
Enceladus II 250 8.40e+19 238,020 W. Herschel 1789
Tethys III 530 7.55e+20 294,660 G. Cassini 1684
Telesto XIII 17x14x13 ? 294,660 B. Smith 1980
Calypso XIV 17x11x11 ? 294,660 B. Smith 1980
Dione IV 560 1.05e+21 377,400 G. Cassini 1684
Helene XII 18x16x15 ? 377,400 Laques-Lecacheux 1980
Rhea V 765 2.49e+21 527,040 G. Cassini 1672
Titan VI 2,575 1.35e+23 1,221,850 C. Huygens 1655
Hyperion VII 205x130x110 1.77e+19 1,481,000 W. Bond 1848
Iapetus VIII 730 1.88e+21 3,561,300 G. Cassini 1671
Phoebe IX 110 4.0e+18 12,952,000 W. Pickering 1898
Possible New Satellites of Saturn
