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 Giantsbrothers 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.

Formation

It is thought that the Saturnian system of Titan, mid-sized moons, and rings developed from a set-up closer to the Galilean moons of Jupiter, though the details are unclear. It has been proposed either that a second Titan-sized moon broke up, producing the rings and inner mid-sized moons, or that two large moons fused to form Titan, with the collision scattering icy debris that formed the mid-sized moons. On 23 June 2014, NASA claimed to have strong evidence that nitrogen in the atmosphere of Titan came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn in earlier times. Studies based on Enceladus's tidal-based geologic activity and the lack of evidence of extensive past resonances in Tethys, Dione, and Rhea's orbits suggest that the moons up to and including Rhea may be only 100 million years old.

Mass distribution

Saturn's satellite system is very lopsided: the largest moon, Titan, comprises more than 96% of the mass in orbit around the planet. The six other planemo moons constitute roughly 4% of the mass. These seven moons are large enough to have collapsed into a relaxed, ellipsoidal shape, though only one or two, Titan and possibly Rhea, are currently in hydrostatic equilibrium. The remaining small moons, together with the rings, comprise only 0.04% of the orbiting mass.
Name
Diameter
Mass
Orbital radius
Orbital period
Mimas396
4×1019
185,539
0.9
Enceladus504
1.1×1020
237,948
1.4
Tethys1,062
6.2×1020
294,619
1.9
Dione1,123
1.1×1021
377,396
2.7
Rhea1,527
2.3×1021
527,108
4.5
Titan5,149
1.35×1023
1,221,870
16
Iapetus1,470
1.8×1021
3,560,820
79

Characteristics and groups

Although the boundaries may be somewhat vague, Saturn's moons can be divided into nine groups according to their orbital characteristics. Many of them, such as Pan and Daphnis, orbit within Saturn's ring system and have orbital periods only slightly longer than the planet's rotation period. The innermost moons and most regular satellites all have mean orbital inclinations ranging from less than a degree to about 1.5 degrees and small orbital eccentricities. On the other hand, irregular satellites in the outermost regions of Saturn's moon system, in particular the Norse group, have orbital radii of millions of kilometers and orbital periods lasting several years. The moons of the Norse group also orbit in the opposite direction to Saturn's rotation.

Ring moons

Ring moons are small satellites that orbit within or near Saturn's rings, playing a crucial role in shaping and maintaining the structure of the rings, keeping them from spreading out, often through orbital resonances. Ring moons can be divided into three dynamical groups: the inner ring moons, the co-orbitals, and the ring-embedded moons.

Inner ring moons

These six satellites orbit the closest to Saturn, occupying spaces between the gaps or on the edges of the main rings. Some of them are shepherd satellites, which have the effect of sculpting the rings: giving them sharp edges, and creating gaps between them. The shepherd moons are Pan, Daphnis, and Prometheus. Atlas and Pandora orbit on the outside edge of the A Ring and F Ring respectively, and were long thought to be shepherds as well, until more recent studies began to indicate otherwise. These moons likely formed as a result of accretion of the friable ring material on preexisting denser cores. The cores with sizes from one-third to one-half the present-day moons may be themselves collisional shards formed when a parental satellite of the rings disintegrated.
During late July 2009, a moonlet, S/2009 S 1, was discovered in the B Ring, 480 km from the outer edge of the ring, by the shadow it cast. It is estimated to be 300 m in diameter. Unlike the A Ring moonlets, it does not induce a 'propeller' feature, probably due to the density of the B Ring. Unlike most other objects referred to as 'moonlets', S/2009 S 1 is counted as a full-fledged moon of Saturn.

Co-orbital moons

and Epimetheus are co-orbital moons. They are of similar size, with Janus being somewhat larger than Epimetheus. They have orbits with less than a 100-kilometer difference in semi-major axis, close enough that they would collide if they attempted to pass each other. Instead of colliding, their gravitational interaction causes them to swap orbits every four years. Both moons additionally act as shepherds for the A Ring.

Ring-embedded moons

These four moons' orbits are embedded within their own faint rings or partial arcs, and serve as sources of material within their respective ring structures.
Aegaeon resides within the bright arc of G Ring and is trapped in the 7:6 mean-motion resonance with Mimas. This means that it makes exactly seven revolutions around Saturn while Mimas makes exactly six. The moon is the largest among the population of bodies that are sources of dust in this ring. The other three moons, Methone, Anthe, and Pallene, are collectively referred to as the Alkyonides, named after those of Greek mythology. Orbiting between the major moons Mimas and Enceladus, they are some of the smallest moons in the Saturn system. Anthe and Methone have very faint ring arcs along their orbits, whereas Pallene has a faint complete ring. Of these three moons, only Methone has been photographed at close range, showing it to be egg-shaped with very few or no craters.
Unlike the other ring-embedded moons, Pallene has no associated arc structure with it. The other moons are in orbital resonances and Pallene is not, and so ejecta from their surfaces remains locked in the same resonance as the moon is, shaping into an arc instead of a complete ring.

Inner large

The inner large moons of Saturn orbit within its tenuous E Ring, along with the three smaller moons of the Alkyonides group and the trojan moons.
  • Mimas is the smallest and least massive of the inner round moons, although its mass is sufficient to alter the orbit of Methone. It is noticeably ovoid-shaped, having been made shorter at the poles and longer at the equator by the effects of Saturn's gravity. Mimas has a large impact crater one-third its diameter, Herschel, situated on its leading hemisphere Mimas has no known past or present geologic activity and its surface is dominated by impact craters, though it does have a water ocean 20–30 km beneath the surface. The only tectonic features known are a few arcuate and linear troughs, which probably formed when Mimas was shattered by the Herschel impact.
  • Enceladus is one of the smallest of Saturn's moons that is spherical in shape—only Mimas is smaller—yet is the only small Saturnian moon that is currently endogenously active, and the smallest known body in the Solar System that is geologically active today. Its surface is morphologically diverse; it includes ancient heavily cratered terrain as well as younger smooth areas with few impact craters. Many plains on Enceladus are fractured and intersected by systems of lineaments. The area around its south pole was found by Cassini to be unusually warm and cut by a system of fractures about 130 km long called "tiger stripes", some of which emit jets of water vapor and dust. These jets form a large plume off its south pole, which replenishes Saturn's E ring and serves as the main source of ions in the magnetosphere of Saturn. The gas and dust are released with a rate of more than 100 kg/s. Enceladus may have liquid water underneath the south-polar surface. The source of the energy for this cryovolcanism is thought to be a 2:1 mean-motion resonance with Dione. The pure ice on the surface makes Enceladus one of the brightest known objects in the Solar System—its geometrical albedo is more than 140%.
  • Tethys is the third largest of Saturn's inner moons. Its most prominent features are a large impact crater named Odysseus on its leading hemisphere and a vast canyon system named Ithaca Chasma extending at least 270° around Tethys. The Ithaca Chasma is concentric with Odysseus, and these two features may be related. Tethys appears to have no current geological activity. A heavily cratered hilly terrain occupies the majority of its surface, while a smaller and smoother plains region lies on the hemisphere opposite to that of Odysseus. The plains contain fewer craters and are apparently younger. A sharp boundary separates them from the cratered terrain. There is also a system of extensional troughs radiating away from Odysseus. The density of Tethys is less than that of water, indicating that it is made mainly of water ice with only a small fraction of rock.
  • Dione is the second-largest inner moon of Saturn. It has a higher density than the geologically dead Rhea, the largest inner moon, but lower than that of active Enceladus. While the majority of Dione's surface is heavily cratered old terrain, this moon is also covered with an extensive network of troughs and lineaments, indicating that in the past it had global tectonic activity. The troughs and lineaments are especially prominent on the trailing hemisphere, where several intersecting sets of fractures form what is called "wispy terrain". The cratered plains have a few large impact craters reaching 250 km in diameter. Smooth plains with low impact-crater counts are also present on a small fraction of its surface. They were probably tectonically resurfaced relatively later in the geological history of Dione. At two locations within smooth plains strange landforms resembling oblong impact craters have been identified, both of which lie at the centers of radiating networks of cracks and troughs; these features may be cryovolcanic in origin. Dione may be geologically active even now, although on a scale much smaller than the cryovolcanism of Enceladus. This follows from Cassini magnetic measurements that show Dione is a net source of plasma in the magnetosphere of Saturn, much like Enceladus.

    Trojan moons

Trojan moons are a unique feature only known from the Saturnian system. A trojan body orbits at either the leading L4 or trailing L5 Lagrange point of a much larger object, such as a large moon or planet. Tethys has two trojan moons, Telesto and Calypso, and Dione also has two, Helene and Polydeuces. Helene is by far the largest trojan moon, while Polydeuces is the smallest and has the most chaotic orbit. These moons are coated with dusty material that has smoothed out their surfaces.

Outer large

These moons all orbit beyond the E Ring.
  • Rhea is the second-largest of Saturn's moons. It is even slightly larger than Oberon, the second-largest moon of Uranus. In 2005, Cassini detected a depletion of electrons in the plasma wake of Rhea, which forms when the co-rotating plasma of Saturn's magnetosphere is absorbed by the moon. The depletion was hypothesized to be caused by the presence of dust-sized particles concentrated in a few faint equatorial rings. Such a ring system would make Rhea the only moon in the Solar System known to have rings. Subsequent targeted observations of the putative ring plane from several angles by Cassini's narrow-angle camera turned up no evidence of the expected ring material, leaving the origin of the plasma observations unresolved.
  • Titan, at 5,149 km diameter, is the second largest moon in the Solar System and Saturn's largest. Out of all the large moons, Titan is the only one with a dense, cold atmosphere, primarily made of nitrogen with a small fraction of methane. The dense atmosphere frequently produces bright white convective clouds, especially over the south pole region. On 6 June 2013, scientists at the IAA-CSIC reported the detection of polycyclic aromatic hydrocarbons in the upper atmosphere of Titan. On 23 June 2014, NASA claimed to have strong evidence that nitrogen in the atmosphere of Titan came from materials in the Oort cloud, associated with comets, and not from the materials that formed Saturn in earlier times.
  • Hyperion is Titan's nearest neighbor in the Saturn system. The two moons are locked in a 4:3 mean-motion resonance with each other, meaning that while Titan makes four revolutions around Saturn, Hyperion makes exactly three. With an average diameter of about 270 km, Hyperion is smaller and lighter than Mimas. It has an extremely irregular shape, and a very odd, tan-colored icy surface resembling a sponge, though its interior may be partially porous as well. The average density of about 0.55 g/cm3 indicates that the porosity exceeds 40% even assuming it has a purely icy composition. The surface of Hyperion is covered with numerous impact craters—those with diameters 2–10 km are especially abundant. It is the only moon besides the small moons of Pluto known to have a chaotic rotation, which means Hyperion has no well-defined poles or equator. While on short timescales the satellite approximately rotates around its long axis at a rate of 72–75° per day, on longer timescales its axis of rotation wanders chaotically across the sky. This makes the rotational behavior of Hyperion essentially unpredictable.
  • Iapetus is the third-largest of Saturn's moons. Orbiting the planet at km, it is by far the most distant of Saturn's large moons, and also has the largest orbital inclination, at 15.47°. Iapetus has long been known for its unusual two-toned surface; its leading hemisphere is pitch-black and its trailing hemisphere is almost as bright as fresh snow. Cassini images showed that the dark material is confined to a large near-equatorial area on the leading hemisphere called Cassini Regio, which extends approximately from 40°N to 40°S. The pole regions of Iapetus are as bright as its trailing hemisphere. Cassini also discovered a 20 km tall equatorial ridge, which spans nearly the moon's entire equator. Otherwise both dark and bright surfaces of Iapetus are old and heavily cratered. The images revealed at least four large impact basins with diameters from 380 to 550 km and numerous smaller impact craters. No evidence of any endogenic activity has been discovered.

    Irregular moons

s are small satellites with distant, inclined, and frequently retrograde orbits, believed to have been acquired by the parent planet through a capture process. They often occur as collisional families or groups. The precise size and albedo of many of the irregular moons are not known because they are too small to be resolved by telescopes on Earth and in space, so their sizes are estimated from their brightness by assuming a dark surface or low albedo of around 6% or less. The irregular moons generally have featureless visible and near infrared spectra dominated by water absorption bands. They are typically gray or moderately red in color—similar to C-type, P-type, or D-type asteroids, though they are much less red than Kuiper belt objects.

Inuit

The Inuit group includes 36 prograde outer moons that are similar enough in their distances from the planet, their orbital inclinations and their colors that they can be considered a group. The Inuit group is further split into three distinct subgroups at different semi-major axes, and are named after their respective largest members. Ordered by increasing semi-major axis, these subgroups are the Kiviuq subgroup, Paaliaq, and the Siarnaq subgroup. It is unknown whether all of these subgroups of the Inuit group share a common origin.
The Kiviuq group includes 20 members, with the only named members being Ijiraq and the group's largest member and namesake Kiviuq. Kiviuq has a diameter of about 17 km and has a highly elongated shape, which may indicate it is a contact binary. The Siarnaq group includes 15 members, with the only named members being Tarqeq and the group's namesake Siarnaq. Siarnaq is the largest member of its subgroup and the entire Inuit group, with an estimated diameter of about 39 km. The moons of the Kiviuq and Siarnaq subgroups are tightly clustered in semi-major axis and inclination with respect to their namesake moon, which makes them distinct collisional families. In contrast to Kiviuq and Siarnaq, Paaliaq does not have an associated subgroup.

Gallic

The Gallic group includes 17 prograde outer moons that are similar in their orbital inclination, their orbital eccentricity, and their color that they can be considered a group. The named members of the Gallic group are Albiorix, Bebhionn, Erriapus, and Tarvos. The largest of these moons is Albiorix with an estimated diameter of about 29 km. The Gallic group may be divided into the Albiorix subgroup, which consists of 16 moons with semi-major axes between 200–330 radii of Saturn, and the outlier moon S/2004 S 24 which has a lower eccentricity and a much more distant semi-major axis of ~400 Saturn radii. S/2004 S 24 may not be directly related to the Gallic group, although it is possible that it could have formed as a fragment of an Albiorix subgroup member that was collisionally disrupted when it was at its farthest distance from Saturn in its elliptical orbit.

Norse

All 197 retrograde outer moons of Saturn are broadly classified into the Norse group. Only 31 moons of the Norse group have been named: Aegir, Angrboda, Alvaldi, Beli, Bergelmir, Bestla, Eggther, Farbauti, Fenrir, Fornjot, Geirrod, Gerd, Greip, Gridr, Gunnlod, Hati, Hyrrokkin, Jarnsaxa, Kari, Loge, Mundilfari, Narvi, Phoebe, Skathi, Skoll, Skrymir, Surtur, Suttungr, Thiazzi, Thrymr, and Ymir.
Although the Norse group does not show obvious clustering in orbital elements, researchers led by Edward Ashton have proposed splitting the Norse group into four different subgroups by inclination. These subgroups still have a broad range of orbital semi-major axes, inclinations, and eccentricities, and may not necessarily have an impact origin.
  • The Phoebe subgroup consists of moons between inclinations 172° and 180° and is named after Phoebe, by far the largest irregular moon of Saturn with a diameter of. It has a retrograde orbit and rotates on its axis every 9.3 hours. Phoebe was the first moon of Saturn to be studied in detail by Cassini, in ; during this encounter Cassini was able to map nearly 90% of the moon's surface. Phoebe has a nearly spherical shape and a relatively high density of about 1.6 g/cm3. Cassini images revealed a dark surface scarred by numerous impacts—there are about 130 craters with diameters exceeding 10 km. Such impacts may have ejected fragments of Phoebe into orbit around Saturn—two of these may be S/2006 S 20 and S/2006 S 9, whose orbits are similar to Phoebe. Spectroscopic measurement showed that the surface is made of water ice, carbon dioxide, phyllosilicates, organics and possibly iron-bearing minerals. Phoebe is believed to be a captured centaur that originated in the Kuiper belt. It also serves as a source of material for the largest known ring of Saturn, which darkens the leading hemisphere of Iapetus.
  • The Mundilfari subgroup consists of moons between inclinations 157° and 172° and is the most populated of the four Norse subgroups proposed by Ashton and collaborators. Named after its largest member Mundilfari, this subgroup is dominated by tiny moons smaller than 4 km in diameter, which suggests they were formed by a relatively recent collisional event that destroyed a progenitor moon at least 100 million years ago. Ashton and collaborators proposed that this progenitor moon of the Mundifari subgroup would have orbited Saturn at a semi-major axis of ~19.5 million km, inclination ~165°, and eccentricity ~0.28. The collision that destroyed this progenitor moon would have to eject its fragments at a speed of at least 200 m/s, and subsequent collisions of its fragments may further disperse their orbits to produce the broad orbital distribution of the Mundilfari group observed today.
  • The Kari subgroup consists of moons between inclinations 151.7° and 157° and appears mostly concentrated around the orbit of its namesake and largest member Kari with a semi-major axis range between from Saturn. This tight clustering may be a collisional family. There are several other moons in the Kari subgroup's inclination range that have semi-major axes less than the aforementioned range, and thus may not be related to the proposed collisional family.
  • The remaining Norse group moons with inclinations below 151.7° are sparse in number and are assigned to the low-inclination subgroup by Ashton and collaborators. Of the moons of the low-inclination subgroup, Narvi and S/2019 S 11 have the most similar orbits to each other, which suggests these two moons share an origin.

    List

The Saturnian moons are listed here by orbital period, from shortest to longest. Moons massive enough for their surfaces to have collapsed into a spheroid are highlighted in bold and marked with a blue background, while the irregular moons are listed in red, orange, green, and gray background. The orbits and mean distances of the irregular moons are strongly variable over short timescales due to frequent planetary and solar perturbations, so the orbital elements of irregular moons listed here are averaged over a 5,000-year numerical integration by the Jet Propulsion Laboratory. These may sometimes strongly differ from the osculating orbital elements provided by other sources. Otherwise, recently discovered irregular moons without published proper elements are temporarily listed here with inaccurate osculating orbital elements that are italicized to distinguish them from other irregular moons with proper orbital elements. The mean orbital elements are based on a reference epoch of 1 January 2000.

Small regular moons Major moons Inuit group Gallic group Norse group

Label
NamePronunciationImageAbs.
magn.

Diameter

Mass

Semi-major
axis


Orbital period
Inclination

Eccentricity
Position
Timeline of discovery of [Solar System planets and their moons|Discovery
year]
Year announcedDiscoverer
S/2009 S 10.3outer B Ring20092009Cassini
Pan9.20.00.000in Encke Division19901990Showalter
Daphnis0.00.000in Keeler Gap20052005Cassini
Atlas8.50.00.00119801980Voyager 1
Prometheus6.70.00.002F Ring shepherd19801980Voyager 1
Pandora6.50.00.00419801980Voyager 1
Epimetheus5.50.30.020co-orbital with Janus19661967Fountain & Larson
Janus4.50.20.007co-orbital with Epimetheus19661967Dollfus
Aegaeon0.00.000G Ring moonlet20082009Cassini
Mimas3.21.60.020 17891789Herschel
Methone0.00.002Alkyonides20042004Cassini
Anthe1.80.00.002Alkyonides20072007Cassini
Pallene0.20.004Alkyonides20042004Cassini
Enceladus2.10.00.005Generates the E ring17891789Herschel
Tethys0.71.10.001 16841684Cassini
Telesto8.71.20.001leading Tethys trojan 19801980Smith et al.
Calypso9.21.50.001trailing Tethys trojan 19801980Pascu et al.
Helene8.20.20.007leading Dione trojan 19801980Laques & Lecacheux
Polydeuces0.20.019trailing Dione trojan 20042004Cassini
Dione0.80.00.002 16841684Cassini
Rhea0.10.30.001 16721673Cassini
Titan–1.30.30.029 16551656Huygens
Hyperion4.80.60.105in 4:3 resonance with Titan18481848Bond & Lassell
Iapetus1.27.60.028 16711673Cassini
♦S/2023 S 116.648.80.386Inuit group 20232025Ashton et al.
S/2019 S 115.349.50.383Inuit group 20192021Ashton et al.
♦S/2004 S 5416.148.10.373Inuit group 20042025Sheppard et al.
♦S/2004 S 5516.548.90.260Inuit group 20042025Sheppard et al.
♦S/2020 S 1116.948.20.372Inuit group 20202025Ashton et al.
♦S/2019 S 2216.747.30.369Inuit group 20192025Ashton et al.
Kiviuq12.748.00.275Inuit group 20002000Gladman et al.
♦S/2023 S 216.745.70.339Inuit group 20232025Ashton et al.
♦S/2019 S 2316.748.70.255Inuit group 20192025Ashton et al.
♦S/2020 S 1216.850.80.260Inuit group 20202025Ashton et al.
♦S/2005 S 415.748.00.315Inuit group 20052023Sheppard et al.
♦S/2019 S 2516.448.10.271Inuit group 20192025Ashton et al.
♦S/2020 S 115.948.20.337Inuit group 20202023Ashton et al.
Ijiraq13.249.20.293Inuit group 20002000Gladman et al.
♦S/2019 S 2416.146.70.345Inuit group 20192025Ashton et al.
♦S/2007 S 1016.145.80.367Inuit group 20072025Sheppard et al.
♦S/2019 S 2616.548.10.365Inuit group 20192025Ashton et al.
♦S/2020 S 1316.548.00.373Inuit group 20202025Ashton et al.
‡S/2023 S 5016.9166.10.263Norse group 20232025Ashton et al.
♦S/2023 S 616.447.40.336Inuit group 20232025Ashton et al.
♦S/2023 S 715.944.70.284Inuit group 20232025Ashton et al.
‡S/2023 S 3817.0149.20.909Norse group 20232025Ashton et al.
Phoebe6.7175.20.164Norse group 18981899Pickering
‡S/2023 S 916.7172.20.141Norse group 20232025Ashton et al.
S/2006 S 2015.8173.10.206Norse group 20062023Sheppard et al.
‡S/2004 S 5615.8161.60.339Norse group 20042025Sheppard et al.
‡S/2023 S 816.7166.90.122Norse group 20232025Ashton et al.
‡S/2023 S 1116.9170.90.300Norse group 20232025Ashton et al.
S/2006 S 916.5173.00.249Norse group 20062023Sheppard et al.
‡S/2006 S 2116.7169.80.204Norse group 20062025Sheppard et al.
Paaliaq11.748.50.378Inuit group20002000Gladman et al.
‡S/2006 S 2216.7172.00.246Norse group 20062025Sheppard et al.
‡S/2023 S 1316.6168.50.179Norse group 20232025Ashton et al.
‡S/2023 S 1016.7163.00.302Norse group 20232025Ashton et al.
Skathi14.3151.60.281Norse group 20002000Gladman et al.
‡S/2023 S 1216.9168.80.601Norse group 20232025Ashton et al.
‡S/2007 S 516.2158.40.104Norse group 20072023Sheppard et al.
‡S/2007 S 716.2169.30.217Norse group 20072023Sheppard et al.
S/2007 S 215.6174.00.232Norse group 20072007Sheppard et al.
S/2004 S 3715.9158.20.448Norse group 20042019Sheppard et al.
‡S/2004 S 4716.3160.90.291Norse group 20042023Sheppard et al.
‡S/2004 S 4016.3169.20.297Norse group 20042023Sheppard et al.
‡S/2020 S 1416.7161.70.313Norse group 20202025Ashton et al.
‡S/2019 S 2716.7162.10.420Norse group 20192025Ashton et al.
Albiorix11.228.636.80.482Gallic group20002000Holman
‡S/2019 S 216.5173.30.279Norse group 20192023Ashton et al.
♣S/2020 S 1516.737.10.462Gallic group20202025Ashton et al.
‡S/2023 S 1416.8171.60.497Norse group 20232025Ashton et al.
‡S/2020 S 1616.5167.30.405Norse group 20202025Ashton et al.
‡S/2023 S 1616.8162.60.270Norse group 20232025Ashton et al.
Bebhionn15.038.60.459Gallic group20042005Sheppard et al.
♣S/2007 S 816.036.20.490Gallic group20072023Sheppard et al.
S/2004 S 2915.738.60.485Gallic group20042019Sheppard et al.
‡S/2019 S 316.2166.90.248Norse group 20192023Ashton et al.
‡S/2020 S 1716.3148.90.378Norse group 20202025Ashton et al.
‡S/2023 S 2016.7136.50.442Norse group 20232025Ashton et al.
♣S/2019 S 2916.537.70.441Gallic group20192025Ashton et al.
♣S/2023 S 1816.836.70.448Gallic group20232025Ashton et al.
♣S/2023 S 1717.135.90.498Gallic group20232025Ashton et al.
‡S/2020 S 716.8161.40.500Norse group 20202023Ashton et al.
♣S/2007 S 1116.335.50.499Gallic group20072025Sheppard et al.
‡S/2019 S 2816.3158.40.199Norse group 20192025Ashton et al.
S/2004 S 3115.648.00.159Inuit group 20042019Sheppard et al.
Erriapus13.737.10.475Gallic group20002000Gladman et al.
♦S/2023 S 1917.048.20.092Inuit group 20232025Ashton et al.
Skoll15.4159.40.463Norse group 20062006Sheppard et al.
♦S/2023 S 316.546.90.178Inuit group 20232025Ashton et al.
‡S/2019 S 3016.8168.30.107Norse group 20192025Ashton et al.
♦S/2020 S 1916.848.10.159Inuit group 20202025Ashton et al.
♣S/2019 S 3116.539.80.488Gallic group20192025Ashton et al.
Tarqeq14.848.70.144Inuit group 20072007Sheppard et al.
‡S/2023 S 2116.9157.30.077Norse group 20232025Ashton et al.
‡S/2023 S 416.4170.00.276Norse group 20232025Ashton et al.
‡S/2020 S 1816.6168.90.180Norse group 20202025Ashton et al.
♦S/2019 S 1416.346.20.172Inuit group 20192023Ashton et al.
‡S/2020 S 216.9170.70.152Norse group 20202023Ashton et al.
Siarnaq10.639.347.80.308Inuit group 20002000Gladman et al.
‡S/2019 S 416.5170.10.408Norse group 20192023Ashton et al.
♦S/2019 S 3215.746.20.276Inuit group 20192025Ashton et al.
‡S/2020 S 2016.6169.80.133Norse group 20202025Ashton et al.
♦S/2020 S 316.446.00.142Inuit group 20202023Ashton et al.
‡S/2004 S 4116.3165.70.301Norse group 20042023Sheppard et al.
♦S/2005 S 616.347.70.084Inuit group 20052025Sheppard et al.
‡S/2004 S 5716.2167.90.263Norse group 20042025Sheppard et al.
♦S/2019 S 615.746.40.120Inuit group 20192023Ashton et al.
‡S/2006 S 2416.8165.90.352Norse group 20062025Sheppard et al.
Tarvos13.137.80.522Gallic group20002000Gladman et al.
S/2020 S 417.040.10.496Gallic group20202023Ashton et al.
‡S/2023 S 3016.7142.40.493Norse group 20232025Ashton et al.
‡S/2004 S 4216.1165.70.158Norse group 20042023Sheppard et al.
‡S/2023 S 1516.8161.90.549Norse group 20232025Ashton et al.
♦S/2004 S 5815.845.70.249Inuit group 20042025Sheppard et al.
♦S/2006 S 2316.443.80.190Inuit group 20062025Sheppard et al.
Hyrrokkin14.3149.90.336Norse group 20042005Sheppard et al.
‡S/2023 S 2416.7169.70.374Norse group 20232025Ashton et al.
Greip15.3174.20.317Norse group 20062006Sheppard et al.
♦S/2020 S 516.648.20.220Inuit group 20202023Ashton et al.
♣S/2019 S 3416.837.60.536Gallic group20192025Ashton et al.
S/2004 S 1316.3169.00.265Norse group 20042005Sheppard et al.
♣S/2005 S 716.434.60.565Gallic group20052025Sheppard et al.
‡S/2007 S 616.4166.50.168Norse group 20072023Sheppard et al.
‡S/2019 S 3516.7157.30.577Norse group 20192025Ashton et al.
‡S/2006 S 2516.4158.80.303Norse group 20062025Sheppard et al.
♦S/2023 S 2216.347.50.182Inuit group 20232025Ashton et al.
Mundilfari14.5167.10.211Norse group 20002000Gladman et al.
‡S/2006 S 2616.5171.90.248Norse group 20062025Sheppard et al.
‡S/2019 S 3316.3170.40.289Norse group 20192025Ashton et al.
S/2006 S 115.7156.10.105Norse group 20062006Sheppard et al.
‡S/2023 S 2316.4164.80.350Norse group 20232025Ashton et al.
‡S/2020 S 2116.7169.90.307Norse group 20202025Ashton et al.
‡S/2004 S 4316.3171.10.432Norse group 20042023Sheppard et al.
‡S/2006 S 1016.4161.60.151Norse group 20062023Sheppard et al.
‡S/2019 S 516.7158.80.216Norse group 20192023Ashton et al.
‡S/2023 S 2517.0166.40.281Norse group 20232025Ashton et al.
‡S/2004 S 5916.4167.30.262Norse group 20042025Sheppard et al.
‡S/2006 S 2716.3170.50.140Norse group 20062025Sheppard et al.
Gridr15.8163.90.187Norse group 20042019Sheppard et al.
Bergelmir15.2158.80.145Norse group 20042005Sheppard et al.
Jarnsaxa15.6163.00.218Norse group 20062006Sheppard et al.
Narvi14.5142.20.441Norse group 20032003Sheppard et al.
‡S/2023 S 4416.6167.40.434Norse group 20232025Ashton et al.
Suttungr14.5175.70.116Norse group 20002000Gladman et al.
‡S/2020 S 2216.6161.30.059Norse group 20202025Ashton et al.
‡S/2004 S 4415.8167.70.129Norse group 20042023Sheppard et al.
‡S/2004 S 6016.5173.80.280Norse group 20042025Sheppard et al.
S/2006 S 1216.238.60.542Gallic group20062023Sheppard et al.
S/2007 S 315.7173.80.150Norse group 20072007Sheppard et al.
‡S/2004 S 4516.0154.00.551Norse group 20042023Sheppard et al.
Hati15.4165.40.372Norse group 20042005Sheppard et al.
S/2004 S 1716.0167.90.162Norse group 20042005Sheppard et al.
‡S/2006 S 1116.5174.10.143Norse group 20042023Sheppard et al.
S/2004 S 1215.9164.70.337Norse group 20042005Sheppard et al.
‡S/2020 S 2316.6165.00.089Norse group 20202025Ashton et al.
‡S/2023 S 2716.5151.10.652Norse group 20232025Ashton et al.
Eggther15.4165.00.157Norse group 20042019Sheppard et al.
‡S/2023 S 2816.9168.70.575Norse group 20232025Ashton et al.
‡S/2023 S 3716.9172.30.215Norse group 20232025Ashton et al.
‡S/2023 S 2616.9163.90.306Norse group 20232025Ashton et al.
‡S/2019 S 3616.8166.90.161Norse group 20192025Ashton et al.
‡S/2006 S 1316.1162.00.313Norse group 20062023Sheppard et al.
‡S/2019 S 3716.7149.90.404Norse group 20192025Ashton et al.
‡S/2023 S 4816.6169.70.022Norse group 20232025Ashton et al.
‡S/2023 S 2916.7172.20.141Norse group 20232025Ashton et al.
‡S/2007 S 916.1159.30.360Norse group 20072023Sheppard et al.
‡S/2019 S 716.3174.20.233Norse group 20192023Ashton et al.
‡S/2019 S 816.3172.80.311Norse group 20192023Ashton et al.
Farbauti15.8156.20.249Norse group 20042005Sheppard et al.
Thrymr14.3175.00.467Norse group 20002000Gladman et al.
Bestla14.6138.30.486Norse group 20042005Sheppard et al.
‡S/2019 S 916.3159.50.433Norse group 20192023Ashton et al.
‡S/2023 S 3217.2169.80.037Norse group 20232025Ashton et al.
‡S/2004 S 4616.4177.20.249Norse group 20042023Sheppard et al.
Angrboda16.1177.70.216Norse group 20042019Sheppard et al.
‡S/2020 S 2416.8159.60.230Norse group 20202025Ashton et al.
‡S/2019 S 1116.3144.60.513Norse group 20192023Ashton et al.
Aegir15.5166.10.255Norse group 20042005Sheppard et al.
‡S/2019 S 1016.7163.90.248Norse group 20192023Ashton et al.
Beli16.1158.90.087Norse group 20042019Sheppard et al.
‡S/2023 S 3117.0163.00.182Norse group 20232025Ashton et al.
‡S/2020 S 2517.0171.80.316Norse group 20202025Ashton et al.
‡S/2023 S 3416.6168.40.570Norse group 20232025Ashton et al.
‡S/2023 S 3916.8164.80.124Norse group 20232025Ashton et al.
‡S/2019 S 1216.3167.10.476Norse group 20192023Ashton et al.
Gerd15.9174.40.517Norse group 20042019Sheppard et al.
‡S/2019 S 1316.7177.30.318Norse group 20192023Ashton et al.
‡S/2004 S 6116.3168.40.466Norse group 20042025Sheppard et al.
‡S/2006 S 1416.5166.70.060Norse group 20062023Sheppard et al.
‡S/2023 S 4016.9169.60.342Norse group 20232025Ashton et al.
Gunnlod15.7160.40.251Norse group 20042019Sheppard et al.
‡S/2019 S 1516.6157.80.257Norse group 20192023Ashton et al.
‡S/2020 S 616.6166.90.480Norse group 20202023Ashton et al.
‡S/2020 S 2616.6163.20.273Norse group 20202025Ashton et al.
‡S/2023 S 4116.7172.10.279Norse group 20232025Ashton et al.
S/2004 S 715.5164.80.511Norse group 20042005Sheppard et al.
S/2006 S 315.7156.10.432Norse group 20062006Sheppard et al.
S/2005 S 516.4169.50.588Norse group 20052023Sheppard et al.
Skrymir15.5175.60.437Norse group 20042019Sheppard et al.
‡S/2023 S 3316.8155.80.665Norse group 20232025Ashton et al.
‡S/2006 S 1616.5164.10.204Norse group 20062023Sheppard et al.
‡S/2023 S 4916.7171.70.026Norse group 20232025Ashton et al.
‡S/2020 S 3016.7154.20.601Norse group 20202025Ashton et al.
‡S/2006 S 1516.2161.10.117Norse group 20062023Sheppard et al.
‡S/2020 S 2716.4145.30.255Norse group 20202025Ashton et al.
‡S/2023 S 4216.7166.70.059Norse group 20232025Ashton et al.
S/2004 S 2815.8167.90.159Norse group 20042019Sheppard et al.
‡S/2020 S 3216.7169.10.502Norse group 20202025Ashton et al.
‡S/2006 S 2816.3172.90.210Norse group 20062025Sheppard et al.
‡S/2020 S 816.4161.80.252Norse group 20202023Ashton et al.
‡S/2020 S 2816.7160.10.474Norse group 20202025Ashton et al.
Alvaldi15.6177.40.238Norse group 20042019Sheppard et al.
‡S/2019 S 3816.7163.00.399Norse group 20192025Ashton et al.
Kari14.5153.00.469Norse group 20062006Sheppard et al.
‡S/2004 S 4816.0161.90.374Norse group 20042023Sheppard et al.
‡S/2023 S 3616.8166.30.359Norse group 20232025Ashton et al.
Geirrod15.9154.40.539Norse group 20042019Sheppard et al.
‡S/2023 S 3516.8168.50.151Norse group 20232025Ashton et al.
‡S/2020 S 2916.8169.10.047Norse group 20202025Ashton et al.
Fenrir15.8164.50.137Norse group 20042005Sheppard et al.
‡S/2004 S 5016.4164.00.450Norse group 20042023Sheppard et al.
‡S/2006 S 1716.0168.70.425Norse group 20062023Sheppard et al.
‡S/2004 S 4916.0159.80.453Norse group 20042023Sheppard et al.
‡S/2020 S 3416.5160.60.154Norse group 20202025Ashton et al.
‡S/2020 S 3116.5163.80.238Norse group 20202025Ashton et al.
‡S/2023 S 4316.4170.30.264Norse group 20232025Ashton et al.
‡S/2019 S 1715.9155.50.546Norse group 20192023Ashton et al.
Surtur15.7168.40.448Norse group 20062006Sheppard et al.
‡S/2006 S 1816.1169.50.131Norse group 20062023Sheppard et al.
‡S/2020 S 3616.6168.80.336Norse group 20202025Ashton et al.
Loge15.4168.10.191Norse group 20062006Sheppard et al.
‡S/2020 S 3316.9162.80.555Norse group 20202025Ashton et al.
Ymir12.2172.30.338Norse group 20002000Gladman et al.
‡S/2020 S 3516.7174.90.225Norse group 20202025Ashton et al.
‡S/2019 S 1916.5151.80.458Norse group 20192023Ashton et al.
‡S/2019 S 1816.6154.60.509Norse group 20192023Ashton et al.
S/2004 S 2116.2153.20.394Norse group 20042019Sheppard et al.
S/2004 S 3916.1165.90.100Norse group 20042019Sheppard et al.
‡S/2019 S 1616.7162.00.250Norse group 20192023Ashton et al.
‡S/2004 S 5316.2162.60.240Norse group 20042023Sheppard et al.
S/2004 S 2416.037.40.071Gallic group20042019Sheppard et al.
S/2004 S 3616.2153.30.625Norse group 20042019Sheppard et al.
‡S/2023 S 4516.9157.40.633Norse group 20232025Ashton et al.
Thiazzi15.9158.80.511Norse group 20042019Sheppard et al.
‡S/2020 S 3816.1159.70.513Norse group 20202025Ashton et al.
‡S/2019 S 2016.7156.00.354Norse group 20192023Ashton et al.
‡S/2020 S 3716.6174.80.344Norse group 20202025Ashton et al.
‡S/2019 S 3916.7174.50.098Norse group 20192025Ashton et al.
‡S/2020 S 4016.6167.30.412Norse group 20202025Ashton et al.
‡S/2006 S 1916.1175.50.467Norse group 20062023Sheppard et al.
‡S/2019 S 4016.6161.80.088Norse group 20192025Ashton et al.
‡S/2019 S 4215.9163.20.121Norse group 20192025Ashton et al.
S/2004 S 3416.1168.30.279Norse group 20042019Sheppard et al.
‡S/2020 S 3916.7160.10.305Norse group 20202025Ashton et al.
‡S/2019 S 4116.9157.10.257Norse group 20192025Ashton et al.
‡S/2023 S 4616.8143.20.336Norse group 20232025Ashton et al.
Fornjot14.7170.00.213Norse group 20042005Sheppard et al.
‡S/2023 S 4717.0162.50.101Norse group 20232025Ashton et al.
‡S/2004 S 5116.1171.20.201Norse group 20042023Sheppard et al.
‡S/2006 S 2916.4156.20.239Norse group 20062025Sheppard et al.
‡S/2020 S 1016.9165.60.296Norse group 20202023Ashton et al.
‡S/2020 S 4216.7157.50.506Norse group 20202025Ashton et al.
‡S/2020 S 916.0161.40.531Norse group 20202023Ashton et al.
‡S/2023 S 516.7168.80.599Norse group 20232025Ashton et al.
‡S/2020 S 4116.6160.20.402Norse group 20202025Ashton et al.
S/2004 S 2615.7172.90.147Norse group 20042019Sheppard et al.
‡S/2019 S 2116.2171.90.155Norse group 20192023Ashton et al.
‡S/2004 S 5216.5165.40.291Norse group 20042023Sheppard et al.
‡S/2020 S 4316.9164.60.203Norse group 20202025Ashton et al.
‡S/2019 S 4316.5165.30.277Norse group 20192025Ashton et al.
‡S/2019 S 4416.4172.60.512Norse group 20192025Ashton et al.
‡S/2020 S 4416.8168.50.199Norse group 20202025Ashton et al.

Other objects

Ring moonlets

Also existing in Saturn's ring system are moonlets: objects generally too small to be counted as moons or directly imaged, and usually short-lived or transient bodies.
In 2006, four tiny moonlets were found in Cassini images of the A Ring. Before this discovery only two larger moons had been known within gaps in the A Ring, Pan and Daphnis, which are large enough to clear continuous gaps in the ring. In contrast, a moonlet is only massive enough to clear two small—about 10 km across—partial gaps in the immediate vicinity of the moonlet itself creating a structure shaped like an airplane propeller. The moonlets themselves are tiny, ranging from about 40 to 500 meters in diameter, and are too small to be seen directly.
In 2007, the discovery of 150 more moonlets revealed that they are confined to three narrow bands in the A Ring between 126,750 and 132,000 km from Saturn's center. Each band is about a thousand kilometers wide, which is less than 1% the width of Saturn's rings. This region is relatively free from the disturbances caused by resonances with larger satellites, although other areas of the A Ring without disturbances are apparently free of moonlets. The moonlets were probably formed from the breakup of a larger satellite. It is estimated that the A Ring contains 7,000–8,000 propellers larger than 0.8 km in size and millions larger than 0.25 km. In April 2014, NASA scientists reported the possible consolidation of a new moon within the A Ring, implying that Saturn's present moons may have formed in a similar process in the past when Saturn's ring system was much more massive.
Similar moonlets may reside in the F Ring. They have not been confirmed as solid bodies; it is not yet clear if these are real satellites or merely persistent clumps within the F Ring. There, "jets" of material may be due to collisions, initiated by perturbations from the nearby small moon Prometheus, of these moonlets with the core of the F Ring. One of the largest F Ring moonlets may be the as-yet unconfirmed object S/2004 S 6. The F Ring also contains transient "fans" which are thought to result from even smaller moonlets, about 1 km in diameter, orbiting near the F Ring core.
The following is a table of selected moonlets observed by Cassini, including unconfirmed bodies.
NameImageDiameter Semi-major
axis
Orbital
period
PositionDiscovery yearStatus
A Ring moonletsThree 1,000 km bands within A Ring2006
S/2004 S 3 and S 4≈ 3–5≈ ≈ +uncertain objects around the F Ring2004Were undetected in thorough imaging of the region in November 2004, making their existence improbable. S/2004 S 4 was most likely a transient clump—it has not been recovered since the first sighting.
S/2004 S 6≈ 3–5≈ +uncertain objects around the F Ring2004Consistently detected into 2005, may be surrounded by fine dust and have a very small physical core

Spurious

Two moons were claimed to be discovered by different astronomers but never seen again. Both moons were said to orbit between Titan and Hyperion.
  • Chiron which was supposedly sighted by Hermann Goldschmidt in 1861, but never observed by anyone else.
  • Themis was allegedly discovered in 1905 by astronomer William Pickering, but never seen again. Nevertheless, it was included in numerous almanacs and astronomy books until the 1960s.

    Hypothetical

In 2022, scientists of the Massachusetts Institute of Technology proposed the hypothetical former moon Chrysalis, using data from the Cassini–Huygens mission. Chrysalis would have orbited between Titan and Iapetus, but its orbit would have gradually become more eccentric until it was torn apart by Saturn. 99% of its mass would have been absorbed by Saturn, while the remaining 1% would have formed Saturn's rings.

Temporary

Much like Jupiter, asteroids and comets will infrequently make close approaches to Saturn, even more infrequently becoming captured into orbit of the planet. The comet P/2020 F1 is calculated to have made a close approach of km to Saturn on 8 May 1936, closer than the orbit of Titan to the planet, with an orbital eccentricity of only. The comet may have been orbiting Saturn prior to this as a temporary satellite, but difficulty modelling the non-gravitational forces makes whether or not it was indeed a temporary satellite uncertain.
Other comets and asteroids may have temporarily orbited Saturn at some point, but none are presently known to have.