Moons of Saturn
has 274 confirmed moons, the most of any planet in the Solar System. Saturn's moons are diverse in size, ranging from tiny moonlets to Titan, which is larger than the planet Mercury and the second largest moon in the Solar System. Three of these moons possess particularly notable features: Titan has a nitrogen-rich, Earth-like atmosphere and a landscape featuring river networks and hydrocarbon lakes, Enceladus emits jets of ice from its south-polar region and is covered in a deep layer of snow, and Iapetus has contrasting black and white hemispheres as well as an extensive ridge of equatorial mountains which are among the tallest in the Solar System.
Twenty-four of the confirmed moons are regular satellites; they have prograde orbits not greatly inclined to Saturn's equatorial plane. They include the seven major satellites, and four small moons that exist in a trojan orbit with some of the large moons. Six orbit near the edges of or within gaps in the main rings, some of which act as shepherd moons of the dense A Ring and the narrow F Ring. Two moons are mutually co-orbital, Janus and Epimetheus. The relatively large Hyperion is locked in an orbital resonance with Titan. The remaining regular moons orbit inside of the diffuse G ring or between the major moons Mimas and Enceladus. The regular satellites are traditionally named after Titans and Titanesses or other figures associated with the mythological Saturn, and one, S/2009 S 1, remains unnamed.
The remaining 250 moons, with mean diameters ranging from, orbit much farther from Saturn. They are irregular satellites, having high orbital inclinations and eccentricities mixed between prograde and retrograde. These moons are probably captured minor planets, or fragments from the collisional breakup of such bodies after they were captured, creating collisional families. The irregular satellites are classified by their orbital characteristics into the prograde Inuit and Gallic groups and the large retrograde Norse group, and their names are chosen from the corresponding mythologies. Phoebe, the largest irregular Saturnian moon, is the sole exception to this naming system; it is part of the Norse group but named for a Greek Titaness. 210 of Saturn's irregular moons are unnamed.
The rings of Saturn are made of objects ranging in size from microscopic to moonlets hundreds of meters across, each in its own orbit around Saturn. The number of moons given above does not include these moonlets, nor hundreds of possible kilometer-sized distant moons that have been observed on single occasions. Thus an absolute number of Saturnian moons cannot be given, because there is no consensus on a boundary between the countless small unnamed objects that form Saturn's ring system and the larger objects that have been named as moons. Over 150 moonlets embedded in the rings have been detected by the disturbance they create in the surrounding ring material, though this is thought to be only a small sample of the total population of such objects.
Discovery
Early observations
Before the advent of telescopic photography, eight moons of Saturn were discovered by direct observation using optical telescopes. Saturn's largest moon, Titan, was discovered in 1655 by Christiaan Huygens using a objective lens on a refracting telescope of his own design. Tethys, Dione, Rhea and Iapetus were discovered between 1671 and 1684 by Giovanni Domenico Cassini. Mimas and Enceladus were discovered in 1789 by William Herschel. Hyperion was discovered in 1848 by W. C. Bond, G. P. Bond and William Lassell.The use of long-exposure photographic plates made possible the discovery of additional moons. The first to be discovered in this manner, Phoebe, was found in 1899 by W. H. Pickering. In 1966 the tenth satellite of Saturn was discovered by Audouin Dollfus, when the rings were observed edge-on near an equinox. It was later named Janus. A few years later it was realized that all observations of 1966 could only be explained if another satellite had been present and that it had an orbit similar to that of Janus. This object is now known as Epimetheus, the eleventh moon of Saturn. It shares the same orbit with Janus—the only known example of co-orbitals in the Solar System. In 1980, three additional Saturnian moons were discovered from the ground and later confirmed by the Voyager probes. They are trojan moons of Dione and Tethys.
Observations by spacecraft
The study of the outer planets has since been revolutionized by the use of uncrewed space probes. The arrival of the Voyager spacecraft at Saturn in 1980–1981 resulted in the discovery of three additional moons—Atlas, Prometheus and Pandora—bringing the total to 17. In addition, Epimetheus was confirmed as distinct from Janus. In 1990, Pan was discovered in archival Voyager images.The Cassini mission, which arrived at Saturn in July 2004, initially discovered three small inner moons: Methone and Pallene between Mimas and Enceladus, and the second trojan moon of Dione, Polydeuces. It also observed three suspected but unconfirmed moons in the F Ring. In Cassini scientists announced that the structure of Saturn's rings indicates the presence of several more moons orbiting within the rings, although only one, Daphnis, had been visually confirmed at the time. In 2007 Anthe was announced. In 2008 it was reported that Cassini observations of a depletion of energetic electrons in Saturn's magnetosphere near Rhea might be the signature of a tenuous ring system around Saturn's second largest moon. In, Aegaeon, a moonlet within the G Ring, was announced. In July of the same year, S/2009 S 1, the first moonlet within the B Ring, was observed. In April 2014, the possible beginning of a new moon, within the A Ring, was reported.
Search for irregulars
Study of Saturn's moons has also been aided by advances in telescope instrumentation, primarily the introduction of digital charge-coupled devices which replaced photographic plates. For the 20th century, Phoebe stood alone among Saturn's known moons with its highly irregular orbit. Then in 2000, a team of astronomers led by Brett J. Gladman discovered twelve irregular moons of Saturn using various ground-based telescopes around the world. The discovery of these irregular moons revealed orbital groupings within Saturn's irregular moon population, which provided the first insights into the collisional history of Saturn's irregular moons.In 2003, a team of astronomers including Scott Sheppard, David C. Jewitt, and Jan Kleyna began using the Subaru 8.2 m telescope at Mauna Kea Observatory to search for irregular moons around Saturn, and discovered Narvi. Because of the Subaru telescope's very large aperture size alongside its camera's large field of view, it is capable of detecting extremely faint moons, hence Sheppard's team continued using the Subaru telescope for further moon searches. In 2005, Sheppard's team announced the discovery of twelve more small outer moons from their Subaru observations. Sheppard's team announced nine more irregular moons in 2006 and three more moons in 2007, when Tarqeq was announced in, followed by S/2007 S 2 and S/2007 S 3 the following month.
No new irregular moons of Saturn were reported until 2019, when Sheppard's team identified twenty more irregular satellites of Saturn in archives of their 2004–2007 Subaru observations. This brought Saturn's moon count to 82, which resulted in Saturn overtaking Jupiter as the planet with the most known moons for the first time since 2000. In 2019, researchers Edward Ashton, Brett Gladman, and Matthew Beaudoin conducted a survey of Saturn's Hill sphere using the 3.6-meter Canada–France–Hawaii Telescope and discovered about 80 new Saturnian irregular moons, which were reported to the Minor Planet Center for announcement. Follow-up observations of these new moons took place over 2019–2021, eventually leading to S/2019 S 1 being announced in November 2021 and an additional 62 moons being announced from 3–16 May 2023. These discoveries brought Saturn's total number of confirmed moons up to 145, making it the first planet known to have over 100 moons. Yet another moon, S/2006 S 20, was announced on 23 May 2023, bringing Saturn's total count moons to 146. On 11 March 2025, 128 moons of Saturn were simultaneously announced by the MPC, bringing the total number of confirmed moons to 274. These moons were found by Ashton, Gladman, Mike Alexandersen, and Jean-Marc Petit, using the CFHT in 2023, as a continuation of their survey. Ashton's team also searched in CFHT images taken by a separate team consisting of Wesley Fraser, Samantha Lawler, and John Kavelaars. Many of these moons were traced back to earlier observations from 2004 to 2021, which correspond to their discovery dates.
All of these recently announced moons are small and faint, with diameters over and apparent magnitudes of 25–27. These extremely dim moons could only be seen via the shift-and-add technique, where multiple long-exposure images are overlaid, shifted to follow the motion of Saturn in the sky, and then additively combined to bring out the signal of faint moons that follow Saturn in the sky. The researchers found that the Saturnian irregular moon population is more abundant at smaller sizes, suggesting that they are likely fragments from a collision that occurred a few hundred million years ago. The researchers extrapolated that the true population of Saturnian irregular moons larger than in diameter amounts to, which is approximately three times as many Jovian irregular moons down to the same size. If this size distribution applies to even smaller diameters, Saturn would therefore intrinsically have more irregular moons than Jupiter.
Naming
The modern names for Saturnian moons were suggested by John Herschel in 1847. He proposed to name them after mythological figures associated with the Roman god of agriculture and harvest, Saturn. In particular, the then known seven satellites were named after Titans, Titanesses and Giants – brothers and sisters of Cronus. The idea was similar to Simon Marius' scheme for naming moons of Jupiter after children of Zeus.As Saturn devoured his children, his family could not be assembled around him, so that the choice lay among his brothers and sisters, the Titans and Titanesses. The name Iapetus seemed indicated by the obscurity and remoteness of the exterior satellite, Titan by the superior size of the Huyghenian, while the three female appellations class together the three intermediate Cassinian satellites. The minute interior ones seemed appropriately characterized by a return to male appellations chosen from a younger and inferior brood.
In 1848, Lassell proposed that the eighth satellite of Saturn be named Hyperion after another Titan. When in the 20th century the names of Titans were exhausted, the moons were named after different characters of the Greco-Roman mythology or giants from other mythologies. All the irregular moons are named after Inuit, and Gallic gods, and after Norse ice giants. The International Astronomical Union's Committee for Planetary System Nomenclature, which oversees the naming of Solar System moons, rules that Saturnian moons that are smaller than 3 km in diameter should only be named if it is of scientific interest.
Some asteroids share the same names as moons of Saturn: 55 Pandora, 106 Dione, 577 Rhea, 1809 Prometheus, 1810 Epimetheus, and 4450 Pan. In addition, three more asteroids would share the names of Saturnian moons if not for spelling differences made permanent by the IAU: Calypso and asteroid 53 Kalypso; Helene and asteroid 101 Helena; and Gunnlod and asteroid 657 Gunlöd.