Saturn's Satellites
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Saturn's Satellites

 Saturn has 18 named satellites plus 13 recently discovered and as yet unnamed ones:
  • Of those moons for which rotation rates are known, all but Phoebe and Hyperion rotate synchronously.
  • The three pairs Mimas-Tethys, Enceladus-Dione and Titan-Hyperion interact gravitationally in such a way as to maintain stable relationships between their orbits: the period of Mimas' orbit is exactly half that of Tethys, they are thus said to be in a 1:2 resonance; Enceladus-Dione are also 1:2; Titan-Hyperion are in a 3:4 resonance.
  • In addition to the 18 named satellites, a dozen more have been reported and given provisional designations but not yet named.

           Distance  Radius    Mass
Satellite  (000 km)   (km)     (kg)   Discoverer   Date
---------  --------  ------  -------  ----------  -----
Pan             134      10     ?     Showalter    1990
Atlas           138      14     ?     Terrile      1980
Prometheus      139      46  2.70e17  Collins      1980
Pandora         142      46  2.20e17  Collins      1980
Epimetheus      151      57  5.60e17  Walker       1980
Janus           151      89  2.01e18  Dollfus      1966
Mimas           186     196  3.80e19  Herschel     1789
Enceladus       238     260  8.40e19  Herschel     1789
Tethys          295     530  7.55e20  Cassini      1684
Telesto         295      15     ?     Reitsema     1980
Calypso         295      13     ?     Pascu        1980
Dione           377     560  1.05e21  Cassini      1684
Helene          377      16     ?     Laques       1980
Rhea            527     765  2.49e21  Cassini      1672
Titan          1222    2575  1.35e23  Huygens      1655
Hyperion       1481     143  1.77e19  Bond         1848
Iapetus        3561     730  1.88e21  Cassini      1671
Phoebe        12952     110  4.00e18  Pickering    1898