Cassini-Huygens Working at Saturn' Moons
Data | click to a view of Saturn's regular moons Hyperion excepted |
Most of what is known about Saturn's moons was yielded by Voyager 1 and 2 missions which reached the ringed planet about 1980. Saturn is surrounded by 31 moons. 8 of them are major regular satellites, 9 are inner moons more or less linked to the ring system as 13 are irregular, newly discovered satellites. Most of Saturn's major moons are more or less cratered. Iapetus interestingly features a surface part dirty ice, part carbonaceous molecules. Titan is distinctly larger than any other Saturn moon. The image pictures all major moons of Saturn, Hyperion excepted. picture © site 'Amateur Astronomy', based on pictures courtesy NASA/JPL-Caltech
| Semimajor axis (in 103km) | Radius (in km) | Orbital Period (in days) | Rotation (in days) | Orbit Inclination (in ° relative to the planet's equator) | Eccentricity | Mass (in 1020 kg) | Mean Density (in kg/m3) | Albedo | |
| Mimas (1) | 185.52 | 209 x 196 x 191 | 0.9424218 | 0.9424218 S | 1.53 | 0.0202 | 0.375 | 1,140 | 0.5 |
| Enceladus | 238.02 | 256 x 247 x 245 | 1.370218 | 1.370218 S | 0.00 | 0.0045 | 0.65 | 1,000 | 1.0 |
| Tethys | 294.66 | 536 x 528 x 526 | 1.887802 | 1.887802 S | 1.86 | 0.0000 | 6.27 | 1,000 | 0.9 |
| Dione | 377.40 | 560 | 2.736915 | 2.736915 S | 0.02 | 0.0022 | 11 | 1,500 | 0.7 |
| Rhea | 527.04 | 764 | 4.517500 | 4.517500 S | 0.35 | 0.0010 | 23.1 | 1,240 | 0.7 |
| Titan | 1,221.83 | 2,575 | 15.945421 | 0.33 | 0.0292 | 1,345.5 | 1,881 | 0.22 | |
| Hyperion | 1,481.1 | 185 x 140 x 113 | 21.276609 | Chaotic | 0.43 | 0.1042 | 0.2 | 1,500 | 0.3 |
| Iapetus | 3,561.3 | 718 | 79.330183 | 79.330183 S | 14.72 | 0.0283 | 15.9 | 1,020 | 0.05 (0.5?) |
| Phoebe | 12,952 | 115 x 110 x 105 | 550.48R | 0.4 | 175.3 | 0.1633 | 0.072 | 1,300 | 0.08 |
(1) back due to its rapid rotation, Mimas has an oblate shape with its diameter at the equator 10 percent larger than at the poles
"S" stands for "synchronous" (moon's rotational period equals moon's orbital period that is the moon, like our Moon, always presents the same face to the planet)
9 minor satellites are found, mostly linked with Saturn ring system from its outer rings to its larger extent. They are ranging in diameter from 6.2 to 59 miles (10 to 95 km). Phoebe is an exception by its distance to Saturn only. It orbits at 8 million miles (13 million km) as it is about 130 miles (200 km) wide. 13 newly discovered satellites are mere rocks ranging in diameter between 3.7 and 20 miles (6-32 km) and orbiting at the far outreaches of the ringed planet between 7.09 and 14.4 million miles (11.4-23.1 million km). picture courtesy JPL, Voyager 2 mission. Smaller bodies are Calypso, Telesto, Helene, and Atlas. Medium-sized are Prometheus, Pandora, and Epimetheus, as larger body is Janus
 | click to a view of Saturn's minor moons Pan and Phoebe excepted |
| Semimajor axis (in 103km) | Radius (in km) | Orbital Period (in days) | Rotation (in days) | Orbit Inclination (in ° relative to the planet's equator) | Eccentricity | Mass (in 1020 kg) | Mean Density (in kg/m3) | Albedo | |
| Pan | 133.583 | 10 | 2.2165 | 0.5750 | 0.0 | 0.000 | 0.00003 | 630 | 0.5 |
| Atlas | 137.670 | 18.5 x 17.2 x 13.5 | 2.2820 | 0.6019 | 0.3 | 0.000 | 0.0001 | 630 | 0.8 |
| Prometheus | 139.353 | 74 x 50 x 34 | 2.2843 | 0.6130 | 0.0 | 0.0024 | 0.0033 | 630 | 0.5 |
| Pandora | 141.700 | 55 x 44 x 31 | 2.3512 | 0.6285 | 0.0 | 0.0042 | 0.0020 | 630 | 0.7 |
| Epimetheus (1) | 151.422 | 69 x 55 x 55 | 0.6942 | 0.6942 S | 0.34 | 0.009 | 0.0054 | 600 | 0.8 |
| Janus (1) | 151.472 | 97 x 95 x 77 | 0.6945 | 0.6945 S | 0.14 | 0.007 | 0.0192 | 650 | 0.9 |
| Calypso | 294.66 | 15 x 8 x 8 | 4.8892 | 1.8878 | ab. 0 | ab. 0 | 0.00004 | 1,000 | 1.0 |
| Telesto | 294.66 | 15 x 12.5 x 7.5 | 4.8892 | 1.8878 | ab. 0 | ab. 0 | 0.00007 | 1,000 | 1.0 |
| Helene | 377.40 | 18 x 16 x 15 | 6.262 | 2.7369 | 0.0 | 0.005 | 0.0003 | 1,500 | 0.7 |
(1) back Janus and Epimetheus' orbits are separated by a mere 30 miles (50 km). The orbits change from inner to outer each 4 years
"S" stands for "synchronous" (moon's rotational period equals moon's orbital period that is the moon, like our Moon, always presents the same face to the planet) OperationsMoons Passages and Flybys
Other Moons
 | Some moons of Saturn only will be the object of a dedicated imaging passage. A special page is dedicated to these imaging passages |
Tethys and Dione Trojans
Miscellaneous
Two of Saturn's moons have Trojan companions that is bodies found 60° ahead and behind of them. Telesto and Calypso are Trojans of Tethys as Helene and Polydeuces of Dione. Polydeuces (S/2004 S5), the second Trojan of Dione was discovered lately only, by Cassini. Trojans satellites are small moons found at gravitationally stable, Lagrangian points ahead or behind a larger moon
 | Seen here, with the massive globe of Saturn, is Telesto, one of Tethys' Trojans. picture courtesy NASA/JPL/Space Science Institute |
 | Best view of Telesto (15 mi -24 km across), this Trojan moon to Tethys along with Calypso (14 mi -22 km across). Telesto is 60° ahead, Calypso 60° behind. Only the shape and no surface features are resolved at the distance of the picture. picture courtesy NASA/JPL/Space Science Institute |
 | Another view of Telesto, unresolved at 477,000 miles (758,000 km). picture courtesy NASA/JPL/Space Science Institute |
 | Taken on Dec. 25, 2005 at a distance of 12,000 miles (20,000 km) from the moon only, this view is showing how the smooth surface of Telesto suggests that the moon is covered with a fine, dust-sized icy material, like Pandora. picture courtesy NASA/JPL/Space Science Institute |
 | This view of Telesto, taken Oct. 11, 2005, is finely showing rock outcrops on the tiny moon. picture courtesy NASA/JPL/Space Science Institute |
 | View of Calypso, the other Trojan of Tethys, at a distance of 63,000 miles (101,000 km). The moon is 14-mile (22-km) wide, as a layer of smoothed debris might cover the surface. Original picture in false color; translated into natural colors by this site. picture courtesy NASA/JPL/Space Science Institute |
 | Helene (20 mi -32 km across), with tiny Polydeuces, are Trojan or 'co-orbital' moons of Dione, orbiting 60 degrees ahead of and behind. picture courtesy NASA/JPL/Space Science Institute |
 | Better details of Helene. picture courtesy NASA/JPL/Space Science Institute |
 | This other view of Helene is well showing how the satellite seems to be buried in its own crater debris, just like Telesto. Image in the visible. picture courtesy NASA/JPL/Space Science Institute |
 | Another view of Helene, in visible green light. picture courtesy NASA/JPL/Space Science Institute |
 | A detailed view of Helene taken in January 2011. picture courtesy NASA/JPL/SSI |
 | A close view of Helene during a flyby on March 3, 2010, toward the anti-Saturn side of Helene, North down and rotated 44 degrees to the left. picture courtesy NASA/JPL/Space Science Institute |
 | Polydeuces (a mere 2 miles -3 km- across!), along with Helene, is a Trojan moon of Dione. picture courtesy NASA/JPL/Space Science Institute |
 | Similar to Earthshine seen at Moon, here is a "Saturnshine" at Dione. It's more important still at Helene. picture courtesy NASA/JPL/Space Science Institute |
 | A "Saturnshine" at Tethys. Both craters on the terminator are Penelope (top) and Antinous (bottom). picture courtesy NASA/JPL/Space Science Institute |
 | Saturnshine at Janus (Aug. 2, 2005; distance 336,000 miles -541,000 km). picture courtesy NASA/JPL/Space Science Institute |
 | Here is a phenomenon which can be particular just to Saturn: a "ringshine"! The light of the Sun is coming from bottom right. It produces the shadow of the globe unto the ring (lower left), as it illuminates the ring from below, with light filtering through. The diffuse light at the lower right of the picture is the "ringshine", that is the light coming from the sunlit side of the ring, projecting unto Saturn's globe. picture courtesy NASA/JPL/Space Science Institute |
