A natural satellite or moon is a celestial body that orbits a planet or smaller body, which is called the primary. s are significant physical entities, associations or structures which current Science has confirmed to exist in Space. In Physics, an orbit is the gravitationally curved path of one object around a point or another body for example the gravitational orbit of a planet around a star A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is Technically, the term natural satellite could refer to a planet orbiting a star, or a dwarf galaxy orbiting a major galaxy, but it is normally synonymous with moon and used to identify non-artificial satellites of planets, dwarf planets, and minor planets. A star is a massive luminous ball of plasma. The nearest star to Earth is the Sun, which is the source of most of the Energy on Earth A dwarf galaxy is a small Galaxy composed of up to several billion Stars a small number compared to our own Milky Way 's 200-400 billion stars This article is about artificial satellites For natural satellites also known as moons see Natural satellite. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded Minor planet is a term used since the 19th century to describe objects such as Asteroids that are in Orbit around the Sun but are not Planets (There are no known natural satellites of moons. )
Two hundred and forty bodies, all in the Solar System, are classified as moons. The Solar System consists of the Sun and those celestial objects bound to it by Gravity. They include 166 orbiting the eight planets,[1] 4 orbiting dwarf planets, and dozens more orbiting small solar system bodies. Small Solar System Body ( SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that Other stars and their planets are very likely to have natural satellites, although none have yet been observed.
The large gas giants have extensive systems of moons, including half a dozen comparable in size to Earth's moon: the four Galilean moons, Saturn's Titan, and Neptune's Triton. A gas giant (sometimes also known as a Jovian planet after the planet Jupiter, or giant planet) is a large Planet that is not primarily EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001 The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek Saturn has an additional six mid-sized moons massive enough to have achieved hydrostatic equilibrium, and Uranus has five. Hydrostatic equilibrium occurs when compression due to Gravity is balanced by a Pressure gradient which creates a Pressure gradient force in the opposite Of the inner planets, Mercury and Venus have no moons at all; Earth has one large moon (the Moon); and Mars has two tiny moons, Phobos and Deimos. The VENUS ( V ictoria E xperimental N etwork U nder the S ea project is a cabled sea floor observatory operated by the University TemplateInfobox Planet.--> Deimos (ˈdaɪməs; also /ˈdiːməs/ Among the dwarf planets, Ceres has no moons (though many objects in the asteroid belt do), Eris has one, Dysnomia, and Pluto has three known satellites, Nix, Hydra, and a large companion called Charon. Ceres (ˈsɪəriːz Dysnomia (,, or as in Greek Δυσνομία officially (136199 Eris I Dysnomia, is the only known moon of the Dwarf planet Eris Nix (ˈnɪks, or as in Greek Νιξ is a Natural satellite of Pluto. Hydra (ˈhaɪdrə, or as in Greek Ύδρα is the outer-most Natural satellite of Pluto. Charon (ˈʃærən; also, as in Χάρων) discovered in 1978 is either the largest Moon of Pluto or the smaller member of a double The Pluto-Charon system is unusual in that the center of mass lies in open space between the two, a characteristic of a double planet system. " Double planet " is an informal term used to describe a Planet with a moon that may be large enough to be considered a planet in its own right a common definition
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Origin
The natural satellites orbiting relatively close to the planet on prograde orbits (regular satellites) are generally believed to have been formed out of the same collapsing region of the protoplanetary disk that gave rise to its primary. A protoplanetary disk (or proplyd) is a rotating Circumstellar disk of dense gas surrounding a young newly formed star a T Tauri star or Herbig star In contrast, irregular satellites (generally orbiting on distant, inclined, eccentric and/or retrograde orbits) are thought to be captured asteroids possibly further fragmented by collisions. In Astronomy, an irregular moon is a Natural satellite following a distant inclined, and often retrograde Orbit. Inclination in general is the Angle between a Reference plane and another plane or axis of direction In Astrodynamics, under standard assumptions, any Orbit must be of Conic section shape Direct motion is the motion of a Planetary body in a direction similar to that of other bodies within its system and is sometimes called prograde motion. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but The Earth's Moon[2] and possibly Charon[3] are exceptions among large bodies in that they are believed to have originated by the collision of two large proto-planetary objects (see the giant impact hypothesis). The material that would have been placed in orbit around the central body is predicted to have reaccreted to form one or more orbiting moons. As opposed to planetary-sized bodies, asteroid moons are thought to commonly form by this process. An asteroid moon is an Asteroid that Orbits another asteroid as its Natural satellite. Triton is another exception, which although large and in a close, circular orbit, is thought to be a captured dwarf planet. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded
Geological activity
Of the nineteen known moons massive enough to have lapsed into hydrostatic equilibrium, several remain geologically active today. Io is the most volcanically active body in the Solar System, while Triton and Enceledus have geysers. TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek TemplateInfobox Planet.--> This article is about the moon of Titan and Triton have significant atmospheres; Titan also has methane lakes, and presumably rain. TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as The lakes of Titan, a moon of Saturn, are bodies of liquid methane that have been detected by the Cassini space probe and had been suspected long Four of the largest moons, Europa, Ganymede, Callisto, and Titan, are thought to have subsurface oceans of liquid water, while smaller Enceladus may have localized subsurface water. TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as TemplateInfobox Planet.--> Ganymede (ˈgænɨmiːd, or as Greek TemplateInfobox Planet.--> Callisto (kəˈlɪstoʊ, or as Greek Many other moons, such as Tethys, show evidence of past geological activity. TemplateInfobox Planet.--> Tethys (ˈtiːθɨs, /ˈtɛθɨs/, or
Orbital characteristics
Tidal locking
The regular natural satellites in the solar system are tidally locked to their primaries, meaning that the same side of the moon always faces the planet. A separate article treats the phenomenon of Tidal resonance in Oceanography. The only known exception is Saturn's moon Hyperion, which rotates chaotically because of the gravitational influence of Titan. TemplateInfobox Planet.--> Hyperion (haɪˈpɪəriən, or as in
In contrast, the outer moons of the gas giants (irregular satellites) are too far away to have become locked. For example, Jupiter's moon Himalia, Saturn's moon Phoebe, and Neptune's moon Nereid have rotation period in the range of ten hours, while their orbital periods are hundreds of days. TemplateInfobox Planet.--> Himalia (, or as in Greek ‘Ιμαλíα TemplateInfobox Planet.--> Phoebe (ˈfiːbi, or as in Greek Nereid (; also as in Greek Νηρηΐδα also known as Neptune II, is a moon of Neptune.
Satellites of satellites
No moons of moons (natural satellites that orbit the natural satellite of another body) are known. In most cases, the tidal effects of the primary would make such a system unstable.
However, calculations performed after the recent detection [4] of a possible ring system around Saturn's moon Rhea indicate that Rhean orbits would be stable. The Saturnian moon Rhea may have a tenuous ring system consisting of three narrow relatively dense bands within a particulate disk TemplateInfobox Planet.--> Rhea (ˈriːə, or as in Greek Furthermore, the suspected rings are thought to be narrow,[5] a phenomenon normally associated with shepherd moons.
Trojan satellites
Two moons are known to have small companions at their L4 and L5 Lagrangian points, sixty degrees ahead and behind the body in its orbit. These companions are called Trojan moons, as their orbits are analogous to the Trojan asteroids of Jupiter. A trojan moon is a Natural satellite of a Planet occupying the L4 or L5 equilateral Lagrangian points of a primary-moon system The Trojan moons are Telesto and Calypso, which are the leading and following companions respectively of Tethys; and Helene and Polydeuces, the leading and following companions of Dione. TemplateInfobox Planet.--> Telesto (tɨˈlɛstoʊ, or as Greek TemplateInfobox Planet.--> Calypso (kəˈlɪpsoʊ, or as in Greek TemplateInfobox Planet.--> Tethys (ˈtiːθɨs, /ˈtɛθɨs/, or TemplateInfobox Planet.--> Helene (ˈhɛlɨni, sometimes, or as TemplateInfobox Planet.--> Dione (daɪˈoʊni, or as in Greek
Asteroid satellites
The discovery of 243 Ida's moon Dactyl in the early 1990s confirmed that some asteroids have moons; indeed, 87 Sylvia has two. An asteroid moon is an Asteroid that Orbits another asteroid as its Natural satellite. TemplateInfobox Planet. --> 243 Ida (ˈaɪdə eye'-də) is a Main belt Asteroid (243 Ida I Dactyl (ˈdæktɨl dak'-tl) is a tiny Asteroid moon (diameter 1 Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but TemplateInfobox Planet. --> 87 Sylvia (ˈsɪlviːə sil'-vee-a) is one of the largest main-belt Some, such as 90 Antiope, are double asteroids with two comparably sized components. 90 Antiope (ænˈtaɪəpi an-tye'-ə-pee) is an Asteroid discovered on October 1, 1866 by Robert Luther.
Natural satellites of the Solar System
The largest natural satellites in the Solar System (those bigger than about 3000 km across) are Earth's moon, Jupiter's Galilean moons (Io, Europa, Ganymede, and Callisto), Saturn's moon Titan, and Neptune's captured moon Triton. The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei. TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as TemplateInfobox Planet.--> Ganymede (ˈgænɨmiːd, or as Greek TemplateInfobox Planet.--> Callisto (kəˈlɪstoʊ, or as Greek TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as Neptune ( English|AmE] ] is the eighth and farthest Planet from the Sun in the Solar System. TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek For smaller moons see the articles on the appropriate planet. In addition to the moons of the various planets there are also over 80 known moons of the dwarf planets, asteroids and other small solar system bodies. A dwarf planet, as defined by the International Astronomical Union (IAU is a Celestial body Orbiting the Sun that is massive enough to be rounded Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but Small Solar System Body ( SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that Some studies estimate that up to 15% of all trans-Neptunian objects could have satellites. A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune.
The following is a comparative table classifying the moons of the solar system by diameter. The column on the right includes some notable planets, dwarf planets, asteroids, and Trans-Neptunian Objects for comparison. It is normal for natural satellites to be named after mythological figures, (predominately Greek), however Uranus's moons are named after Shakespearean characters. The nineteen bodies massive enough to have achieved hydrostatic equilibrium are in bold. Hydrostatic equilibrium occurs when compression due to Gravity is balanced by a Pressure gradient which creates a Pressure gradient force in the opposite Those suspected but not proven to have achieved a hydrostatic equilibrium are italicized.
Terminology
The first known natural satellite was the Moon (luna in Latin). Small Solar System Body ( SSSB) is a term defined in 2006 by the International Astronomical Union to describe objects in the Solar System that TemplateInfobox Planet.--> Ganymede (ˈgænɨmiːd, or as Greek TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as TemplateInfobox Planet.--> Callisto (kəˈlɪstoʊ, or as Greek TemplateInfobox Planet.--> Io (ˈaɪoʊ, or as Greek TemplateInfobox Planet.--> Europa (jʊˈroʊpə; or as TemplateInfobox Planet.--> Triton (ˈtraɪtən, or as in Greek TemplateInfobox Planet.--> Rhea (ˈriːə, or as in Greek Titania (, also) is the largest moon of Uranus and the eighth largest moon in the Solar System. TemplateInfobox Planet.--> Oberon (ˈoʊbərɒn) is the outermost TemplateInfobox Planet.--> 90377 Sedna (ˈsɛdnə) is a Trans-Neptunian TemplateInfobox Planet.--> Iapetus (aɪˈæpɨtəs, or as in Greek TemplateInfobox Planet.--> Dione (daɪˈoʊni, or as in Greek TemplateInfobox Planet.--> Tethys (ˈtiːθɨs, /ˈtɛθɨs/, or Umbriel (ˈʌmbriəl) is a moon of Uranus discovered on October 24, 1851 by William Lassell. TemplateInfobox Planet.--> Ariel (ˈɛəriəl) is a moon Charon (ˈʃærən; also, as in Χάρων) discovered in 1978 is either the largest Moon of Pluto or the smaller member of a double TemplateInfobox Planet. --> 90482 Orcus (, Orcus originally known by the Provisional designation TemplateInfobox Planet.--> This article is about the moon of Ceres (ˈsɪəriːz This article is about 20000 Varuna, a minor planet For other uses of the word see Varuna (disambiguation 20000 Varuna ( TemplateInfobox Planet. --> 28978 Ixion (ɪkˈsaɪən ik-SYE-ən, sometimes TemplateInfobox Planet. --> 2 Pallas (ˈpæləs, or as Παλλάς) is one of the largest TemplateInfobox Planet. --> 4 Vesta (ˈvɛstə Vesta is the second most massive object in the Asteroid belt A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. TemplateInfobox Planet. --> Mimas (ˈmaɪməs, or as Greek TemplateInfobox Planet.--> Hyperion (haɪˈpɪəriən, or as in TemplateInfobox Planet.--> Miranda (mɨˈrændə) is the smallest There is also an Asteroid called 9313 Protea. Nereid (; also as in Greek Νηρηΐδα also known as Neptune II, is a moon of Neptune. Dysnomia (,, or as in Greek Δυσνομία officially (136199 Eris I Dysnomia, is the only known moon of the Dwarf planet Eris TemplateInfobox Planet. --> 511 Davida (dəˈviːdə də-VEE-də is a large TemplateInfobox Planet. --> 704 Interamnia (ˌɪntərˈæmniə in'-tər-am'-nee-ə from Latin TemplateInfobox Planet.--> Amalthea (, or as in Greek Αμάλθεια TemplateInfobox Planet.--> Himalia (, or as in Greek ‘Ιμαλíα TemplateInfobox Planet.--> Thebe (, or as in Greek Θήβη TemplateInfobox Planet.--> Phoebe (ˈfiːbi, or as in Greek Saturn X redirects here For the spurious moon reported in 1905 see Themis (moon TemplateInfobox Planet.--> Epimetheus (ˌɛpɨˈmiːθiəs,, or Orbit Sycorax follows a distant orbit more than 20 times further from Uranus than the furthest regular moon Oberon. TemplateInfobox Planet.--> Puck (ˈpʌk puk' is an Portia (por'-shə ˈpɔrʃə is an Inner satellite of Uranus. Discovery It was first discovered by Harold J Reitsema, William B See also A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. TemplateInfobox Planet.--> Elara (, or as in Greek Ελάρα TemplateInfobox Planet.--> Pasiphaë (, or as in Greek Πασιφάη TemplateInfobox Planet.--> Prometheus (proʊˈmiːθiəs,, or There is also an Asteroid called 55 Pandora. See also Uranus' natural satellites Irregular satellites There is also an Asteroid called 1285 Julietta. TemplateInfobox Planet.--> Belinda (bə-lin'-də bɨˈlɪndə There is also an Asteroid called 548 Kressida. There is also an Asteroid called 900 Rosalinde. There is also a Minor planet called 666 Desdemona. There is also an Asteroid called 218 Bianca. Halimede (, or as in Greek Αλιμήδη is a retrograde Irregular satellite of Neptune. Neso (, or as in Greek Νησώ also known as Neptune XIII, is the outermost Irregular natural satellite of Neptune. Nix (ˈnɪks, or as in Greek Νιξ is a Natural satellite of Pluto. Hydra (ˈhaɪdrə, or as in Greek Ύδρα is the outer-most Natural satellite of Pluto. 617 Patroclus (pə-troe'-kləs pəˈtroʊkləs is a binary Minor planet made up of two similarly-sized objects orbiting their common Centre 90 Antiope (ænˈtaɪəpi an-tye'-ə-pee) is an Asteroid discovered on October 1, 1866 by Robert Luther. A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. Carme (, or as in Greek Κάρμη is a retrograde irregular satellite of Jupiter. TemplateInfobox Planet.--> Metis (, or as in Greek Μήτις TemplateInfobox Planet.--> Sinope (, or as in Greek Σινώπη TemplateInfobox Planet.--> Lysithea (,, or as in Greek Λυσιθέα TemplateInfobox Planet.--> Ananke (, or as in Greek Ανάγκη There is also an Asteroid named 38 Leda. ---- Adrastea (, or as in Greek Αδράστεια also known as Jupiter XV, is the second by distance and the smallest of the four inner moons of Jupiter Siarnaq (ˈsiːɑrnɑːk SEE-ar-naak or Saturn XXIX, is a Prograde irregular satellite of Saturn. TemplateInfobox Planet.--> Helene (ˈhɛlɨni, sometimes, or as Albiorix (ˌælbiːˈɔrɨks AL-bee-OR-iks is a Prograde irregular satellite of Saturn. TemplateInfobox Planet.--> Atlas (ˈætləs, or as Greek Άτλας For the moon of Jupiter known by this name 1955-1975 see Carme (moon. TemplateInfobox Planet.--> Telesto (tɨˈlɛstoʊ, or as Greek Paaliaq (ˈpɑːliɑːk PAH-lee-ahk is a Prograde irregular satellite of Saturn. TemplateInfobox Planet.--> Calypso (kəˈlɪpsoʊ, or as in Greek Ymir (ˈɪmɪr IM-irr or Saturn XIX is a retrograde Irregular moon of Saturn. Kiviuq (ˈkiːvioʊk KEE-vee-ohk or KIV-ee-ook is a Prograde irregular satellite of Saturn Tarvos (ˈtɑrvəs TAR-vəs or ˈtɑrvɒs TAR-vos or Saturn XXI is a Prograde irregular satellite Ijiraq (ˈiːɨrɑːk EE-yə-rahk or EE-jə-rahk is a Prograde irregular satellite of Saturn Erriapus (ˌɛriˈæpəs ERR-ee-AP-əs or as Latin Erriapus Erriappus also Saturn XXVIII, is a Prograde There is also an Asteroid called 171 Ophelia. TemplateInfobox Planet.--> Cordelia (kor-dee'-lee-ə See also Uranus' natural satellites Irregular satellites * Patagonia See also Uranus' natural satellites Irregular satellites Perdita (pər'-di-tə ˈpɝdɨtə is an Inner satellite of Uranus. See also Uranus' natural satellites Irregular satellites See also Uranus' natural satellites Irregular satellites Orbit Ferdinand is the most distant known satellite of Uranus Orbit Margaret stands out as the only prograde irregular satellite of Uranus See also Uranus' natural satellites Irregular satellites Sao (, or as in Greek Σαώ is a prograde Irregular satellite of Neptune. Laomedeia (,, or as in Greek Λαομέδεια also known as Neptune XII, is a prograde Irregular satellite of Neptune. Psamathe (, or as in Latin Psamathē Greek Ψαμάθη TemplateInfobox Planet. --> (22 Kalliope I Linus is an Asteroid moon that orbits the large M-type 762 Pulcova TemplateInfobox Planet. --> Romulus is the outer and larger moon of the Main belt Asteroid TemplateInfobox Planet. --> (45 Eugenia I Petit-Prince is an Asteroid moon that orbits the larger asteroid 283 Emma is a large main belt Asteroid. It was discovered by Auguste Charlois on February 8, 1889 in Nice. A trans-Neptunian object (TNO is any object in the Solar system that Orbits the sun at a greater distance on average than Neptune. 2006 RH120 is the provisional designation for a small Asteroid, with a diameter estimated at two meters which ordinarily orbits the Sun but temporarily TemplateInfobox Planet.--> Deimos (ˈdaɪməs; also /ˈdiːməs/ Jupiter has 62 confirmed moons, giving it the largest retinue of moons with "reasonably secure" orbits of any planet in the Solar System Saturn has 60 confirmed moons. These include 22 regular satellites, which all have Prograde orbits that are not greatly inclined with respect Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. Until the discovery of the Galilean satellites in 1610, however, there was no opportunity for referring to such objects as a class. The Galilean moons are the four moons of Jupiter discovered by Galileo Galilei. Galileo chose to refer to his discoveries as Planetæ ("planets"), but later discoverers chose other terms to distinguish them from the objects they orbited. Galileo Galilei (15 February 1564 &ndash 8 January 1642 was a Tuscan ( Italian) Physicist, Mathematician, Astronomer, and Philosopher A planet, as defined by the International Astronomical Union (IAU is a celestial body Orbiting a Star or stellar remnant that is
Christiaan Huygens, the discoverer of Titan, was the first to use the term moon for such objects, calling Titan Luna Saturni or Luna Saturnia – "Saturn's moon" or "The Saturnian moon", because it stood in the same relation to Saturn as the Moon did to the Earth. Christiaan Huygens (ˈhaɪgənz in English ˈhœyɣəns in Dutch) ( April 14, 1629 &ndash July 8, 1695) was a Dutch TemplateInfobox Planet.--> Titan (ˈtaɪtən, or as EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001
As additional moons of Saturn were discovered, however, this term was abandoned. Giovanni Domenico Cassini sometimes referred to his discoveries as planètes in French, but more often as satellites, using a term derived from the Latin satelles, meaning "guard", "attendant", or "companion", because the satellites accompanied their primary planet in their journey through the heavens. Giovanni Domenico Cassini ( June 8, 1625 &ndash September 14, 1712) was an Italian Mathematician, Astronomer French ( français,) is a Romance language spoken around the world by 118 million people as a native language and by about 180 to 260 million people
The term satellite thus became the normal one for referring to an object orbiting a planet, as it avoided the ambiguity of "moon". In 1957, however, the launching of the artificial object Sputnik created a need for new terminology. The terms man-made satellite or artificial moon were very quickly abandoned in favor of the simpler satellite, and as a consequence, the term has come to be linked primarily with artificial objects flown in space – including, sometimes, even those which are not in orbit around a planet.
As a consequence of this shift in meaning, the term moon, which had continued to be used in a generic sense in works of popular science and in fiction, has regained respectability and is now used interchangeably with satellite, even in scientific articles. When it is necessary to avoid both the ambiguity of confusion with the Earth's moon on the one hand, and artificial satellites on the other, the term natural satellite (using "natural" in a sense opposed to "artificial") is used.
The definition of a moon
There is no established lower limit on what should be considered a moon. Every body with an identified orbit, some as small as a kilometer across, has been identified as a moon, though objects a tenth that size within Saturn's rings, which have not been directly observed, have been called moonlets. Small asteroid moons, such as Dactyl, have also been called moonlets. (243 Ida I Dactyl (ˈdæktɨl dak'-tl) is a tiny Asteroid moon (diameter 1
The upper limit is also vague. When the masses of two orbiting bodies are similar enough that one cannot be said to orbit the other, they are described as a double body rather than primary and satellite. " Double planet " is an informal term used to describe a Planet with a moon that may be large enough to be considered a planet in its own right a common definition Asteroids such as 90 Antiope are considered double asteroids, but they have not forced a clear definition as to what constitutes a moon. Asteroids, sometimes called Minor planets or planetoids', are bodies—primarily of the inner Solar System —that are smaller than planets but 90 Antiope (ænˈtaɪəpi an-tye'-ə-pee) is an Asteroid discovered on October 1, 1866 by Robert Luther. Some authors consider the Pluto-Charon system to be a double (dwarf) planet. The most common dividing line on what is considered a moon rests upon whether the barycentre is below the surface of the larger body, though this is somewhat arbitrary, as it relies on distance as well as relative mass.
See also
- Co-orbital moon
- Extrasolar moon
- Inner moon
- Irregular moon
- List of moons
- List of moons by diameter
- Naming of moons
- Quasi-satellite
- Timeline of discovery of Solar System planets and their moons
- Trojan moon
Moons of planets
Moons of dwarf planets and small Solar System bodies
- Asteroid moon
- Moons of Pluto
- Eris' moon
- Moons of 2003 EL61
Notes and references
- ^ List of natural satellites orbiting the planets.
- ^ R. Co-orbital moons are Natural satellites that orbit at the same (or very similar distance from their parent Planet as each other An extrasolar moon, or exomoon, is a term that refers to a smaller natural (non-man-made Satellite In Astronomy, an inner moon is a Natural satellite following a prograde, low inclination Orbit inwards of the large satellites of In Astronomy, an irregular moon is a Natural satellite following a distant inclined, and often retrograde Orbit. This list of moons restricts itself to the Natural satellites of Planets and Dwarf planets that have secured orbits The tables below of Natural satellites in the Solar System are ordered from largest to smallest by average diameter The naming of moons has been the responsibility of the IAU 's committee for Planetary System Nomenclature since 1973 A quasi-satellite is an object in a 11 Orbital resonance with its Planet that stays close to the planet over many orbital periods Wikipedia talkFeatured lists for an explanation of this and other inclusion tags below-->This timeline of discovery of Solar System planets and their natural A trojan moon is a Natural satellite of a Planet occupying the L4 or L5 equilateral Lagrangian points of a primary-moon system Mars has two tiny moons, Phobos and Deimos, which are thought to be captured Asteroids If viewed from the surface Jupiter has 62 confirmed moons, giving it the largest retinue of moons with "reasonably secure" orbits of any planet in the Solar System Saturn has 60 confirmed moons. These include 22 regular satellites, which all have Prograde orbits that are not greatly inclined with respect Uranus has twenty-seven named moons. Five of them are massive enough to have achieved Hydrostatic equilibrium and so would be considered Dwarf planets Neptune has thirteen known moons. The largest by far is Triton, discovered by William Lassell just seventeen days after the discovery of Neptune itself An asteroid moon is an Asteroid that Orbits another asteroid as its Natural satellite. Pluto has three known moons. The largest Charon, is proportionally larger compared to its primary than any other satellite of a known planet or dwarf planet in Dysnomia (,, or as in Greek Δυσνομία officially (136199 Eris I Dysnomia, is the only known moon of the Dwarf planet Eris Canup and E. Asphaug (2001). "Origin of the Moon in a giant impact near the end of the Earth's formation". Nature 412: 708-712.
- ^ S. Stern, H. Weaver, A. Steffl, M. Mutchler, W. Merline, M. Buie, E. Young, L. Young, and J. Spencer (2006). "A giant impact origin for Pluto's small moons and satellite multiplicity in the Kuiper belt". Nature 439: 946-949.
- ^ The Dust Halo of Saturn's Largest Icy Moon, Rhea -- Jones et al. 319 (5868): 1380 -- Science. Retrieved on 2008-03-06. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1079 - Omar Khayyám completes the Iranian calendar. 1454 - Thirteen Years' War: Delegates of
- ^ Saturn satellite reveals first moon rings - 06 March 2008 - New Scientist. Retrieved on 2008-03-06. 2008 ( MMVIII) is the current year in accordance with the Gregorian calendar, a Leap year that started on Tuesday of the Common Events 1079 - Omar Khayyám completes the Iranian calendar. 1454 - Thirteen Years' War: Delegates of
- ^ a b Diameters of the new Plutonian satellites are still very poorly known, but they are estimated to lie between 44 and 130 km.
- ^ (617) Patroclus I Menoetius
- ^ (22) Kalliope I Linus
- ^ (87) Sylvia I Romulus
- ^ (45) Eugenia I Petit-Prince
External links
Jupiter's moons
- Scott Sheppard on Jupiter's satellites
- Jupiter's new moons (discovered in 2000)
- Jupiter's new moons (discovered in 2002)
- Jupiter's new moons (discovered in 2003)
Saturn's moons
All moons
- Natural Satellite Physical Parameters (JPL-NASA, with refs—last updated July 2006)
- Moons of the Solar System (The Planetary Society, as of July 2006)
- Scott Sheppard's page
- Major moons in order from the Sun
- JPL's Solar System Dynamics page
- Moon of an Object? First Photo of Satellite Beyond the Solar System
- USGS list of named moons
- Upper size limit for moons explained
- Asteroids with Satellites
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