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Encyclopedia > Janus (moon)
Janus
Image:Janus 2006 closeup.jpg
Janus in front of Saturn, as imaged by Cassini
Discovery
Discovered by: Audouin Dollfus
Discovery date: December 15, 1966
Orbital characteristics[1]
Epoch 31 December 2003 (JD 2453005.5)
Semi-major axis: 151,460 ± 10 km
Eccentricity: 0.0068
Orbital period: 0.694660342 d
Inclination: 0.163 ± 0.004° to Saturn's equator
Satellite of: Saturn
Physical characteristics
Dimensions: 193×173×137 km [2]
Mean radius: 89 ± 3 [2]
Mass: 1.912 ± 0.005 ×1018 kg [1]
Mean density: 0.64 ± 0.06 g/cm³
Equatorial surface gravity: ~0.0137 m/s2
Rotation period: synchronous
Axial tilt: zero
Albedo: 0.71 ± 0.02 (geometric)[3]

Janus (jay'-nus, IPA: [ˈdʒeɪnəs], Greek Ιανός) is an inner satellite of Saturn. It is also known as Saturn X (Roman numeral X = 10). It is named after the mythological Janus. Image File history File links Metadata No higher resolution available. ... Audouin Charles Dollfus (November 12, 1924 – ) is a French astronomer. ... is the 349th day of the year (350th in leap years) in the Gregorian calendar. ... Year 1966 (MCMLXVI) was a common year starting on Saturday (link will display full calendar) of the 1966 Gregorian calendar. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... In astronomy, an epoch is a moment in time for which celestial coordinates or orbital elements are specified. ... is the 365th day of the year (366th in leap years) in the Gregorian calendar. ... Year 2003 (MMIII) was a common year starting on Wednesday of the Gregorian calendar. ... The Julian day or Julian day number (JDN) is the integer number of days that have elapsed since the initial epoch defined as noon Universal Time (UT) Monday, January 1, 4713 BC in the proleptic Julian calendar [1]. That noon-to-noon day is counted as Julian day 0. ... The semi-major axis of an ellipse In geometry, the term semi-major axis (also semimajor axis) is used to describe the dimensions of ellipses and hyperbolae. ... A kilometer (Commonwealth spelling: kilometre), symbol: km is a unit of length in the metric system equal to 1,000 metres (from the Greek words χίλια (khilia) = thousand and μέτρο (metro) = count/measure). ... (This page refers to eccitricity in astrodynamics. ... The orbital period is the time it takes a planet (or another object) to make one full orbit. ... For the science fiction novella by William Shunn, see Inclination (novella). ... A natural satellite is an object that orbits a planet or other body larger than itself and which is not man-made. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... This article or section is in need of attention from an expert on the subject. ... “Kg” redirects here. ... For other uses, see Density (disambiguation). ... The surface gravity of a Killing horizon is the acceleration, as exerted at infinity, needed to keep an object at the horizon. ... Acceleration is the time rate of change of velocity and/or direction, and at any point on a velocity-time graph, it is given by the slope of the tangent to the curve at that point. ... In astronomy, a rotation period is the time an astronomical object takes to complete one revolution around its rotation axis relative to the background stars. ... Due to synchronous rotation of their moon, the inhabitants of the central body will never be able to see its green side. ... In astronomy, axial tilt is the inclination angle of a planets rotational axis in relation to a perpendicular to its orbital plane. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ... The geometric albedo of an astronomical body is the ratio of its total brightness at zero phase angle to that of an idealised fully reflecting, diffusively scattering (Lambertian) disk with the same cross-section. ... Articles with similar titles include the NATO phonetic alphabet, which has also informally been called the “International Phonetic Alphabet”. For information on how to read IPA transcriptions of English words, see IPA chart for English. ... In astronomy, an inner satellite is a natural satellite following a prograde, low inclination orbit inwards of the large satellites of the parent planet. ... Atmospheric characteristics Atmospheric pressure 140 kPa Hydrogen >93% Helium >5% Methane 0. ... Roman bust of Janus, Vatican. ...

Contents

Discovery and orbit

The following is a summary. For more detailed information about Janus and Epimetheus' unusual shared orbit, see Epimetheus.

Janus occupies essentially the same orbit as the moon Epimetheus. This caused some confusion for astronomers, who assumed that there was only one body in that orbit, and for a long time struggled to figure out what was going on. It was eventually realised that they were trying to reconcile observations of two distinct objects as a single object. Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ...


The discovery of Janus is attributed to its first observer: Audouin Dollfus, on December 15, 1966.[4] The new object was given the temporary designation S/1966 S 2. Previously, Jean Texereau had photographed Janus on October 29, 1966 without realising it; Dollfus named it at the same occasion.[5] On December 18, Richard Walker made a similar observation which is now credited as the discovery of Epimetheus.[6] Audouin Charles Dollfus (November 12, 1924 – ) is a French astronomer. ... is the 349th day of the year (350th in leap years) in the Gregorian calendar. ... Year 1966 (MCMLXVI) was a common year starting on Saturday (link will display full calendar) of the 1966 Gregorian calendar. ... is the 302nd day of the year (303rd in leap years) in the Gregorian calendar. ... Year 1966 (MCMLXVI) was a common year starting on Saturday (link will display full calendar) of the 1966 Gregorian calendar. ... is the 352nd day of the year (353rd in leap years) in the Gregorian calendar. ... Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ...


Twelve years later, in October 1978, Stephen M. Larson and John W. Fountain realised that the 1966 observations were best explained by two distinct objects (Janus and Epimetheus) sharing very similar orbits.[7] (See below for a more detailed description of their unique arrangement.) Year 1978 (MCMLXXVIII) was a common year starting on Sunday (link displays the 1978 Gregorian calendar). ...


Janus was observed on subsequent occasions and given different provisional designations. It was observed by the Pioneer 11 probe when it passed near Saturn on September 1, 1979: three energetic particle detectors observed its "shadow" (S/1979 S 2.[8]) Janus was observed by Dan Pascu on February 19, 1980 (S/1980 S 1,[9]) and then by John W. Fountain, Stephen M. Larson, Harold J. Reitsema and Bradford A. Smith on the 23rd (S/1980 S 2.[10]) Position of Pioneer 10 and 11 Pioneer 11 was the second mission to investigate Jupiter and the outer solar system and the first to explore the planet Saturn and its main rings. ... is the 244th day of the year (245th in leap years) in the Gregorian calendar. ... Also: 1979 by Smashing Pumpkins. ... [[Media:Italic text]]{| style=float:right; |- | |- | |} is the 50th day of the year in the Gregorian calendar. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... Harold J. Reitsema is an astronomer who discovered Larissa, which is the fifth of Neptunes known moons. ...


The Voyager 1 probe finally confirmed Janus' existence on March 1, 1980.[citation needed] All of these people thus share, to various degrees, the title of discoverer of Janus. For the album by The Verve, see Voyager 1 (album). ... is the 60th day of the year (61st in leap years) in the Gregorian calendar. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ...


Name

Janus is named after Janus, the two-faced Roman god. Although the name was informally proposed soon after the initial 1966 discovery,[5] it was not officially given this name until 1983.[11] Epimetheus received its name at the same time. Roman bust of Janus, Vatican. ... A head of Minerva found in the ruins of the Roman baths in Bath Roman mythology, the mythological beliefs of the people of Ancient Rome, can be considered as having two parts. ... Year 1966 (MCMLXVI) was a common year starting on Saturday (link will display full calendar) of the 1966 Gregorian calendar. ... Year 1983 (MCMLXXXIII) was a common year starting on Saturday (link displays the 1983 Gregorian calendar). ... In Greek mythology, Epimetheus (hindsight, literally hind-thought) was the brother of Prometheus (foresight, literally fore-thought), a pair of Titans who acted as representatives of mankind (Kerenyi 1951, p 207). ...


According to the OED, the adjectival form of the moon's name is Janian. The Oxford English Dictionary print set The Oxford English Dictionary (OED) is a dictionary published by the Oxford University Press (OUP), and is the most successful dictionary of the English language, (not to be confused with the one-volume Oxford Dictionary of English, formerly New Oxford Dictionary of English, of... In grammar, an adjective is a word whose main syntactic role is to modify a noun or pronoun (called the adjectives subject), giving more information about what the noun or pronoun refers to. ...


Orbital relationship between Epimetheus and Janus

Janus and Epimetheus are "co-orbital". Janus is currently slightly closer to Saturn than Epimetheus. As smaller orbits have higher velocities, Janus moves faster than Epimetheus, approaching it. Since Epimetheus' diameter is 115 km and Janus' is 178 km, and the orbital radiuses differ only by about 50 km, a collision seems inevitable. But as the inner moon catches up with the outer moon their mutual gravitational attraction boosts the inner moon's momentum and raises its orbit, causing it to slow down. The outer moon, in turn, loses an equal amount of momentum and drops into a lower orbit at the same time, effectively speeding it up. The moons thus "trade" orbits and begin moving apart again, without completely overtaking each other and without even approaching each other closely (no closer than about 10,000 km). The exchange takes place about once every four years; the last close approach was on 21 January 2006,[12] the next will be in 2010. At that time, Janus' orbital radius will increase by ~20 km, while Epimetheus' decreases by ~80 km (Janus' orbit is less affected because it is 4 times more massive than Epimetheus). This arrangement is unique in the solar system, as far as is currently known. Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... Co-orbital moons are natural satellites that orbit at the same distance from their parent planet as another satellite, or at a similar distance. ... Two bodies with a slight difference in mass orbiting around a common barycenter. ... is the 21st day of the year in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... 2010 (MMX) will be a common year starting on Friday of the Gregorian calendar. ... This article is about the Solar System. ...


The orbital relationship between Janus and Epimetheus can be understood in terms of the circular restricted three-body problem, as a case in which the two moons (the third body being Saturn) are similar in size to each other. Other examples of the three-body problem include Trojan asteroids and Trojan moons, the "horseshoe" orbit of Cruithne with respect to Earth, and potentially dozens of other objects in similar orbits.[13] The n-body problem is the problem of finding, given the initial positions, masses, and velocities of n bodies, their subsequent motions as determined by classical mechanics, i. ... This article is about the planet. ... As originally defined, Trojan asteroids have a semi-major axis between 5. ... A Trojan moon is a natural satellite of a planet occupying the L4 or L5 equilateral Lagrangian points of a primary-moon system. ... A horseshoe orbit is the type of orbit you get when you observe an object from another nearly co-orbital object, such as a planet. ... 3753 Cruithne (pronounced , Modern Irish ) is an asteroid in orbit around the Sun. ...


Physical characteristics

Janus is extensively cratered with several craters larger than 30 km but few linear features. The Janian surface appears to be older than Prometheus' but younger than Pandora's. From its very low density and relatively high albedo, it seems likely that Janus is a very porous icy body. There is a lot of uncertainty in these values, however, and so this remains to be confirmed. Prometheus (proe-mee-thee-us, Greek Προμηθέας) is a moon of Saturn. ... Pandora (pan-dor-a, Greek Πανδώρα) is a moon of Saturn. ... Albedo is the ratio of reflected to incident electromagnetic radiation. ...


Ring

A faint dust ring is present around the region occupied by the orbits of Janus and Epimetheus, as revealed by images taken in forward-scattered light by the Cassini spacecraft in 2006. The ring has a radial extent of about 5,000 km.[14] Its source are particles blasted off the moons' surfaces by meteoroid impacts, which then form a diffuse ring around their orbital paths.[15] This is an artists concept of Cassini during the Saturn Orbit Insertion (SOI) maneuver, just after the main engine has begun firing. ...


Janus in literature

The moon Janus features prominently in the science fiction novel Pushing Ice by Alastair Reynolds. In the novel, Janus is a camouflaged alien spaceship which unexpectedly takes off in the direction of a giant structure orbiting the star Spica. The novel tells the story of the crew of a human mining ship who establish a colony on the moon as it leaves the solar system. Pushing Ice is a 2005 science fiction novel by Welsh author Alastair Reynolds (ISBN 0575074388). ... Alastair Reynolds (born in 1966 in Barry, South Wales) is a Welsh science fiction author. ... Spica (α Vir / α Virginis / Alpha Virginis) is the brightest star in the constellation Virgo, and one of the brightest stars in the nighttime sky. ... This article is about the Solar System. ...


See also

This is list of named geological features on Janus, Epimetheus and Phoebe. ... Saturn and its moons Several of Saturns natural satellites of have figured prominently in works of science fiction. ...

References

  1. ^ a b Spitale, J. N.; et al. (2006). "The orbits of Saturn's small satellites derived from combined historic and Cassini imaging observations". The Astronomical Journal 132: 692. 
  2. ^ a b Porco, C. C.; et al. (2006). "Physical Characteristics and Possible Accretionary Origins for Saturn's Small Satellites". Bulletin of the American Astronomical Society 37: 768. 
  3. ^ Verbiscer, A.; French, R.; Showalter, M.; and Helfenstein, P.; Enceladus: Cosmic Graffiti Artist Caught in the Act, Science, Vol. 315, No. 5813 (February 9, 2007), p. 815 (supporting online material, table S1)
  4. ^ IAUC 1987: Probable New Satellite of Saturn 1967 January 3 (discovery)
  5. ^ a b IAUC 1995: Saturn X (Janus) 1967 February 1 (naming the moon)
  6. ^ IAUC 1991: Possible New Satellite of Saturn 1967 January 6
  7. ^ Fountain, J. W.; and Larson, S. M.; Saturn's ring and nearby faint satellites, Icarus, Vol. 36 (October 1978), pp. 92–106
  8. ^ IAUC 3417: New Ring and Satellites of Saturn 1979 October 25
  9. ^ IAUC 3454: Saturn 1980 February 25
  10. ^ IAUC 3456: 1980 S 2 1980 February 29
  11. ^ Transactions of the International Astronomical Union, Vol. XVIIIA, 1982 (confirms Janus, names Epimetheus, Telesto, Calypso) (mentioned in IAUC 3872: Satellites of Jupiter and Saturn, 1983 September 30)
  12. ^ NASA JPL, Cassini-Huygens Multimedia: The Dancing Moons, May 3, 2006
  13. ^ Lloyd, R.; More Moons Around Earth? Its Not So Loony, Space.com, 29 October 1999
  14. ^ NASA Planetary Photojournal, PIA08328: Moon-Made Rings
  15. ^ Cassini-Huygens press release, NASA Finds Saturn's Moons May Be Creating New Rings, 11 October 2006

Carolyn C. Porco is an American planetary scientist. ... Richard French (June 20, 1792 - May 1, 1854) was a U.S. Representative from Kentucky. ... is the 40th day of the year in the Gregorian calendar. ... Year 2007 (MMVII) is the current year, a common year starting on Monday of the Gregorian calendar and the AD/CE era. ... Year 1967 (MCMLXVII) was a common year starting on Sunday (link will display full calendar) of the 1967 Gregorian calendar. ... is the 3rd day of the year in the Gregorian calendar. ... Year 1967 (MCMLXVII) was a common year starting on Sunday (link will display full calendar) of the 1967 Gregorian calendar. ... is the 32nd day of the year in the Gregorian calendar. ... Year 1967 (MCMLXVII) was a common year starting on Sunday (link will display full calendar) of the 1967 Gregorian calendar. ... is the 6th day of the year in the Gregorian calendar. ... Also: 1979 by Smashing Pumpkins. ... is the 298th day of the year (299th in leap years) in the Gregorian calendar. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... is the 56th day of the year in the Gregorian calendar. ... Year 1980 (MCMLXXX) was a leap year starting on Tuesday (link displays the 1980 Gregorian calendar). ... February 29 is a day added into a leap year of the Gregorian calendar. ... Year 1982 (MCMLXXXII) was a common year starting on Friday (link displays the 1982 Gregorian calendar). ... Year 1983 (MCMLXXXIII) was a common year starting on Saturday (link displays the 1983 Gregorian calendar). ... is the 273rd day of the year (274th in leap years) in the Gregorian calendar. ... is the 123rd day of the year (124th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ... is the 302nd day of the year (303rd in leap years) in the Gregorian calendar. ... This article is about the year. ... is the 284th day of the year (285th in leap years) in the Gregorian calendar. ... Year 2006 (MMVI) was a common year starting on Sunday of the Gregorian calendar. ...

External links

... | Epimetheus | Janus | Mimas | ...
v • d • e
Moons of Saturn
Generally listed in increasing distance from Saturn. Temporary names in italics.
Ring shepherds Pan · Daphnis · Atlas · Prometheus · S/2004 S 6? · S/2004 S 4? · S/2004 S 3? · Pandora
Co-orbitals Epimetheus · Janus
Inner large
(and Trojan)

Mimas · Methone · Anthe · Pallene · Enceladus · Tethys (Telesto • Calypso) · Dione (Helene • Polydeuces) Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... Mimas (mee-mÉ™s or mye-mÉ™s, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... The Saturnian system (photographic montage) Saturn has 60 confirmed natural satellites, plus three hypothetical moons. ... This article is about the planet. ... Atmosphere none Pan (pan, Greek Πάν) is a moon of Saturn, named after the god Pan. ... Atmosphere none Daphnis (IPA: , Greek Δαφνίς) is an inner satellite of Saturn. ... Atmospheric pressure 0 kPa Atlas (at-lus, Greek Άτλας) is a moon of Saturn. ... Prometheus (proe-mee-thee-us, Greek Προμηθέας) is a moon of Saturn. ... S/2004 S 6 is the provisional designation of a natural satellite of Saturn that was discovered in 2004 (on October 28 images) by the Cassini probe team, led by Carolyn C. Porco et al. ... S/2004 S 4 is the designation of an unconfirmed moon of Saturn announced by the Cassini Imaging Team on September 9, 2004. ... S/2004 S 3 is the provisional designation of an unconfirmed moon of Saturn. ... Pandora (pan-dor-a, Greek Πανδώρα) is a moon of Saturn. ... Epimetheus (ep-i-mee-thee-us, Greek Επιμηθεύς) is a moon of Saturn. ... Mimas (mee-mÉ™s or mye-mÉ™s, IPA: , Greek Μίμᾱς, rarely Μίμανς) is a moon of Saturn that was discovered in 1789 by William Herschel. ... Discovery image of Methone Methone (me-thoe-nee, Greek Μεθωνη) is a natural satellite of Saturn. ... Anthe is a very small natural satellite of Saturn lying between the orbits of Mimas and Enceladus. ... Discovery image of Pallene Pallene (pa-lee-nee, Greek Παλλήνη) is a natural satellite of Saturn. ... Atmosphere Surface pressure: trace, significant spatial variability[8][9] Composition: 91% Water vapour 4% Nitrogen 3. ... Atmosphere none Tethys (tee-thÉ™s or teth-É™s, IPA , Greek Τηθύς) is a moon of Saturn that was discovered by Giovanni Domenico Cassini in 1684. ... Atmosphere none Telesto IPA: , Greek Τελεστώ) is a moon of Saturn. ... Atmosphere none Calypso (ka-lip-soe, Greek Καλυψώ) is a moon of Saturn. ... Atmosphere none Dione (dye-oe-nee, Greek Διώνη) is a moon of Saturn discovered by Giovanni Cassini in 1684. ... Helene (hel-e-nee, Greek ‘Ελένη) is a moon of Saturn. ... Saturns moon Polydeuces Atmosphere none Polydeuces (pol-ee-dew-seez, IPA: , Greek Πολυδεύκης) is a very small natural satellite of Saturn that is co-orbital with Dione and librates around the trailing Lagrangian point (L5). ...

Outer large Rhea · Titan · Hyperion · Iapetus
Inuit group Kiviuq · Ijiraq · Paaliaq · Siarnaq · Tarqeq
Norse group

Phoebe · Skathi · S/2007 S 2 · Skoll · S/2004 S 13 · Greip · Hyrrokkin · Mundilfari · Jarnsaxa · S/2006 S 1 · S/2004 S 17 · Narvi · Bergelmir · Aegir · Suttungr · S/2004 S 12 · Bestla · Farbauti · Hati · S/2004 S 7 · Thrymr · S/2007 S 3 · S/2006 S 3 · Surtur · Kari · Fenrir · Ymir · Loge · Fornjot Atmosphere none Rhea (ree-a, Greek ‘Ρέα) is the second largest moon of Saturn and was discovered in 1672 by Giovanni Domenico Cassini. ... Titan (, from Ancient Greek Τῑτάν) or Saturn VI is the largest moon of Saturn and the only moon known to have a dense atmosphere. ... Hyperion (IPA: , Greek Ὑπερίων) is a moon of Saturn discovered by William Cranch Bond, George Phillips Bond and William Lassell in 1848. ... Iapetus (eye-ap-É™-tÉ™s, IPA , Greek Ιαπετός) is the third-largest moon of Saturn, discovered by Giovanni Domenico Cassini in 1671. ... The Inuit group is made up of moons of Saturn which share similar orbits. ... Kiviuq (kee-vee-oek or kiv-ee-uk) is a natural satellite of Saturn. ... Ijiraq (ee-ye-raak or ee-ji-raak) is a natural satellite of Saturn. ... Paaliaq (paw-lee-aak) is a natural satellite of Saturn. ... Siarnaq (see-ar-naak) (Saturn XXIX) is a natural satellite of Saturn. ... Tarqeq, or Saturn LII (provisional designation S/2007 S 1) is a natural satellite of Saturn. ... The Norse group is a large group of moons of Saturn which share similar orbits. ... For other meanings see Phoebe. ... Skathi (skaadh-ee, with a voiced th as in this) (Saturn XXVII) is a natural satellite of Saturn. ... S/2007 S 2 is a natural satellite of Saturn. ... Skoll, or Saturn XLVII (provisional designation S/2006 S 8) is a retrograde irregular satellite of Saturn. ... S/2004 S 13 is a natural satellite of Saturn. ... Greip, or Saturn LI (provisional designation S/2006 S 4) is a natural satellite of Saturn. ... Hyrrokkin, or Saturn XLIV (provisional designation S/2004 S 19) is a natural satellite of Saturn. ... Mundilfari (moon-dil-fair-ee, Norse Mundilfäri) (Saturn XXV) is a natural satellite of Saturn. ... Jarnsaxa, or Saturn L (provisional designation S/2006 S 6) is a natural satellite of Saturn. ... S/2006 S 1 is a natural satellite of Saturn. ... S/2004 S 17 is a natural satellite of Saturn. ... Narvi (nar-vee) (Saturn XXXI) is a natural satellite of Saturn. ... Bergelmir, or Saturn XXXVIII (provisional designation S/2004 S 15) is a natural satellite of Saturn. ... Aegir (IPA: ), or Saturn XXXVI (provisional designation S/2004 S 10) is a natural satellite of Saturn. ... Suttungr (soot-oong-ur) (Saturn XXIII) is a natural satellite of Saturn. ... S/2004 S 12 is a natural satellite of Saturn. ... Bestla, or Saturn XXXIX (provisional designation S/2004 S 18) is a natural satellite of Saturn. ... Farbauti, or Saturn XL (provisional designation S/2004 S 9) is a natural satellite of Saturn. ... Hati, or Saturn XLIII (provisional designation S/2004 S 14) is a natural satellite of Saturn. ... S/2004 S 7 is a natural satellite of Saturn. ... Thrymr (THRIM er) is a natural satellite of Saturn. ... S/2007 S 3 is a natural satellite of Saturn. ... S/2006 S 3 is a natural satellite of Saturn. ... Surtur, or Saturn XLVIII (provisional designation S/2006 S 7) is a natural satellite of Saturn. ... Kari, or Saturn XLV (provisional designation S/2006 S 2) is a natural satellite of Saturn. ... Fenrir, or Saturn XLI (provisional designation S/2004 S 16) is a natural satellite of Saturn. ... Ymir (ee-mur) (Saturn XIX) is a natural satellite of Saturn. ... Loge, or Saturn XLVI (provisional designation S/2006 S 5) is a natural satellite of Saturn. ... Fornjot (IPA: ), or Saturn XLII (provisional designation S/2004 S 8) is a natural satellite of Saturn. ...

Gallic group Albiorix · Bebhionn · Erriapo · Tarvos
Rings of Saturn · Cassini-Huygens · Themis

]] The Gallic group is made up of moons of Saturn which share similar orbits. ... Albiorix (al-bee-or-iks) is a natural satellite of Saturn. ... Bebhionn, or Saturn XXXVII (provisional designation S/2004 S 11) is a natural satellite of Saturn. ... Erriapo (air-ee-ap-oe?, Latin Erriapō or Erriappō) (Saturn XXVIII) is a natural satellite of Saturn. ... Tarvos (tar-vus) (Saturn XXI) is a natural satellite of Saturn. ... The full set of rings, as photographed by the Cassini spacecraft on September 15, 2006 (brightness has been exaggerated in this image). ... Cassini-Huygens is a joint NASA/ESA/ASI unmanned space mission intended to study Saturn and its moons. ... On April 28, 1905, William H. Pickering, who had seven years earlier discovered PhÅ“be, announced the discovery of a tenth satellite of Saturn, which he promptly named Themis. ...


  Results from FactBites:
 
NationMaster - Encyclopedia: Janus (moon) (3925 words)
The orbital relationship between Janus and Epimetheus can be understood in terms of the circular restricted three-body problem, as a case in which the two moons (the third body being Saturn) are similar in size to each other.
A faint dust ring is present around the region occupied by the orbits of Janus and Epimetheus, as revealed by images taken in forward-scattered light by the Cassini spacecraft in 2006.
Janus and Epimetheus may have formed from a disruption of a single parent to form co-orbital satellites, but if this is the case the disruption must have happened early in the history of the satellite system.
Epimetheus (moon) - Wikipedia, the free encyclopedia (557 words)
The name Janus was officially approved by the IAU at the same time, although the name had been used informally since Dollfus proposed it a few days after the 1966 discovery.
Since closer orbits have higher velocities the two moons must inevitably approach each other, and since Epimetheus' diameter is 115 km and Janus' is 178 km it would seem at first glance that a collision is also inevitable.
Janus and Epimetheus may have formed from a disruption of a single parent to form co-orbital satellites, but if this is the case the disruption must have happened early in the history of the satellite system.
  More results at FactBites »

 

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