The 21 largest satellites of Saturn
The 21 largest satel­lites of Sat­urn
Image 1/2, Credit: NASA/JPL/David Seal

The 21 largest satellites of Saturn

In the up­per half of the il­lus­tra­tion, the 21 largest Sat­urn satel­lites are rep­re­sent­ed full-scale with re­spect to each oth­er and in re­la­tion to the par­ent plan­et (beige cir­cu­lar seg­ment un­der the moons) and to the rings (in the back­ground). The low­er half shows the po­si­tions of sev­er­al of the moons up to a dis­tance of ap­prox­i­mate­ly sev­en Sat­urn radii from the plan­et's cen­tre, which can be seen as an out­line hemi­sphere hav­ing a ra­dius of 71,500 kilo­me­tres at the left (shown in cor­rect full scale).
Titan's upper atmosphere in ultraviolet
Ti­tan's up­per at­mo­sphere in ul­tra­vi­o­let
Image 2/2, Credit: NASA/JPL/Space Science Institute

Titan's upper atmosphere in ultraviolet

Ti­tan's up­per at­mo­sphere in ul­tra­vi­o­let. Sev­er­al dust lay­ers are eas­i­ly rec­og­niz­able.

It is really no surprise that people talk about the Saturn system as being an analogy of the Solar System. This is a world of unique complexity, made up of a central body and its satellites, not to mention the famous ring surrounding the planet at its equator. Saturn is also being orbited by a man-made satellite, the space probe Cassini, which will remain in orbit around the planet until at least 2017. The orbiter will perform repeated fly-bys of the planet's moons at various distances and at different orbital inclinations, gathering scientific data from every conceivable angle.

Like the gas giant Jupiter, the largest planet in the Solar System, the moons of Saturn vary enormously in their composition and the age of their surfaces. With the exception of Titan, however, Saturn's moons are much smaller than Jupiter's four large moons: Ganymede (the largest satellite in the Solar System), Callisto, Io and Europa, known collectively as the 'Galilean' moons after the astronomer who discovered them.

Like the Galilean moons, the moons of Saturn (except Io) are composed primarily of ice, mixed with varying proportions of rock and, in some cases, organic substances (carbon compounds). As well as photographically documenting the surface geology using the camera system on board the Cassini spacecraft, another principal objective of the Cassini-Huygens mission is to study the chemical and mineralogical composition of the planet's moons using the spectrometers onboard the Cassini probe (and in the case of Titan, the Huygens lander).

Titan's upper atmosphere in ultraviolet

Titan, the second largest moon in the Solar System (its diameter of 5150 kilometres makes it even larger than Mercury and Pluto), has one unique feature: its dense atmosphere of nitrogen and methane. This is one of the features that rank Titan amongst the most important targets of exploration in the outer Solar System.

The European atmospheric and lander probe Huygens was taken on a six-year journey to Saturn by Cassini with the express aim of exploring the mysterious moon. The Huygens probe touched down on Titan's icy-cold (-180º) surface of frozen methane on 14 January 2005 after a three-hour parachute descent, during which it took important measurements and pictures.

The first of Saturn's satellites were discovered in the 17th century by the Italian-French astronomer Giovanni Cassini (1625-1712) and his Dutch contemporary Christiaan Huygens (1629-1695). However, it was the two US Pioneer probes, and later Voyager I and II, that provided us in 1980 with the first close-up pictures of these unknown worlds, providing the stimulus for the most ambitious project ever launched in the exploration of the outer Solar System: the US-European probe Cassini-Huygens.

Classifying Saturn's moons is no easy task, but categorising them by size puts Titan at the top of the list by a considerable amount. There are four much smaller moons, with diameters ranging from 1060 to 1530 kilometres: Rhea, Iapetus, Dione and Tethys. Then there are three moons whose diameters range from almost 200 to 500 kilometres: Enceladus, Mimas and Hyperion. These moons are also known as the 'main' satellites.

Saturn's moon Enceladus above the planet's rings

Janus, Phoebe, Epimetheus, Prometheus and Pandora, the largest of the smaller satellites, are not at all spherical in shape, and each has a diameter of between 10 and 100 kilometres. Then there are a dozen satellites barely more than 10 kilometres in diameter, starting with Siarnaq, which measures 40 kilometres. Finally, there are numerous irregularly shaped satellites, with sizes of less than 10 kilometers.

A dozen of these minuscule moons were discovered using what was then the largest reflecting telescope in the world, on Mauna Kea in Hawaii. Eleven of these bodies orbit Saturn in the opposite direction to the planet's own direction of rotation, supporting the idea that they were not formed together with the planet in their current location in the Solar System, but originated in the 'comet reservoir' of the Kuiper Belt between the orbital paths of Uranus, Neptune and Pluto before being captured by Saturn's gravitational force. Analyses performed by the VIMS spectrometer on board Cassini suggest that the 200 kilometre diameter moon Phoebe may be of similar origin. The hypothesis that many of these small, irregular bodies do not originate within the Saturn system but in other regions of the Solar System is also supported by the fact that these moons often have orbital inclinations that deviate markedly from the plane of the equator.

Known moons of Saturn (as of 12/2005)

Name of

Astronomical designation

Diameter (km)

Distance_to_ Saturn centre (km)


Titan 5,1501,221,9001655: Christiaan Huygens
Rhea 1,528527,1001672: Giovanni Cassini
Iapetus 1,4363,560,8001671: Giovanni Cassini
Dione 1,118377,4001684: Giovanni Cassini
Tethys 1,060294,700 1684: Giovanni Cassini
Enceladus 499238,100 1789: William Herschel
Mimas 397185,600 1789: William Herschel
Hyperion 2661,464,100 1848: W.&G. Bond; W. Lassell
JanusS/1980 S 1178151,500 1980: Audouin Dollfus
Phoebe 12012,944,300 1898: W.H. Pickering / D.L. Stewart
EpimetheusS/1980 S 3119151,400 1980: R. Walker
PrometheusS/1980 S 27100139,400 1980: S. Collins
PandoraS/1980 S 2684141,7001980: S. Collins
SiarnaqS/2000 S 34018,160,0002000: Gladman & Kavelaars
Atlas S/1980 S 28 32137,700 1980: Richard Terrile 
Helene S/1980 S 6 32377,400 1980: P. Lacques & J. Lecacheux 
Albiorix S/2000 S 11 3216,404,000 2000: Matthew Holman 
Telesto S/1980 S 13 24 294,700 1980: B. Smith et al. 
Paaliaq S/2000 S 2 22 15,199,000 2000: Brett Gladman 
Pan S/1980 S 13 20 133,600 1981: Mark Showalter 
Calypso S/1980 S 25 19 294,700 1980: D. Pascu et al. 
Ymir S/2000 S 1 18 23,096,000 2000: Brett Gladman 
Kiviuq S/2000 S 5 16 11,365,000 2000: Brett Gladman 
Tarvos S/2000 S 4 15 18,247,000 2000: Kavelaars & Gladman
Ijiraq S/2000 S 6 12 11,440,000 2000: Kavelaars & Gladman 
Erriapo S/2000 S 10 10 17,616,000 2000: Kavelaars & Gladman 
Skathi (Skadi) S/2000 S 8 815,647,000 2000: Kavelaars & Gladman 
Daphnis S/2005 S 1 7136,500 2005: Cassini ISS Team 
Mundilfari  S/2000 S 9 718,709,000 2000: Gladman & Kavelaars 
Narvi S/2003 S 1 718,719,000 2003: Sheppard et al. 
Suttungr S/2000 S 12 719,463,000 2000: Gladman & Kavelaars 
Bestla S/2004 S 18 719,650,000 2004: David Jewitt et al. 
Thrymr S/2000 S 7 720,382,000 2000: Gladman & Kavelaars 
Bebhionn S/2004 S 11 616,950,000 2004: S.S. Shepard 
 S/2004 S 13 618,450,000 2004: David Jewitt et al. 
Bergelmir S/2004 S 15 618,750,000 2004: David Jewitt et al. 
Aegir S/2004 S 10 619,350,000 2004: David Jewitt et al. 
 S/2004 S 7 619,800,000 2004: David Jewitt et al. 
Hati S/2004 S 14 619,950,000 2004: David Jewitt et al. 
Fornjot S/2004 S 8 622,200,000 2004: David Jewitt et al. 
 S/2004 S 12 519,650,000 2004: David Jewitt et al. 
Farbauti S/2004 S 9 519,800,000 2004: David Jewitt et al. 
Pallene S/2004 S 2 4211,000 2004: Charnóz & Porco 
Polydeuces S/2004 S 5 4377,400 2004: Carolyn Porco 
Hyrrokin S/2004 S 19 418,600,000 2004: David Jewitt et al. 
Fenrir S/2004 S 16 422,200,000 2004: David Jewitt et al. 
Methone S/2004 S 1 3194,000 2004: Charnóz & Porco 

Saturn's rings




D66,970 km7,540 km
C74,510 km17,490 km
B92,000 km25,580 km
A122,170 km14,610 km
F140,180 km50 km
G170,180 km500 to several thousand km
E181,000 km302,000 km

Distance is from Saturn's centre to closest edge of ring.

  • Elke Heinemann
    Ger­man Aerospace Cen­ter (DLR)

    Com­mu­ni­ca­tions and Me­dia Re­la­tions
    Telephone: +49 2203 601-2867
    Linder Höhe
    51147 Cologne
  • Ulrich Köhler
    Ger­man Aerospace Cen­ter (DLR)
    In­sti­tute of Plan­e­tary Re­search
    Rutherfordstraße 2
    12489 Berlin

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