"deemed important as controllers of the earth and seas. It is a common modern misconception to attribute Neptune to just the seas; however, in Greek myth Neptune is the ruler of earth and all it possesses, just as Zeus is the ruler of the heavens and Hades is the ruler of the Underworld. Triton is actually the character attributed to ruler of (just) the seas. Neptune and Triton are often depicted in water-like settings, holding tridents and usually driving chariots that have horses shooting out from the water. Bernini's sculpture gives a slightly different representation of the duo. The story"
"formed ""in situ"". Triton and Nereid are unusual irregular satellites and are thus treated separately from the other five irregular Neptunian moons, which are more like the outer irregular satellites of the other outer planets. Firstly, they are the largest two known irregular moons in the Solar System, with Triton being almost an order of magnitude larger than all other known irregular moons. Secondly, they both have atypically small semi-major axes, with Triton's being over an order of magnitude smaller than those of all other known irregular moons. Thirdly, they both have unusual orbital eccentricities: Nereid has one of the"
"most eccentric orbits of any known irregular satellite, and Triton's orbit is a nearly perfect circle. Finally, Nereid also has the lowest inclination of any known irregular satellite. Triton follows a retrograde and quasi-circular orbit, and is thought to be a gravitationally captured satellite. It was the second moon in the Solar System that was discovered to have a substantial atmosphere, which is primarily nitrogen with small amounts of methane and carbon monoxide. The pressure on Triton's surface is about 14 μbar. In 1989 the ""Voyager 2"" spacecraft observed what appeared to be clouds and hazes in this thin atmosphere."
"orbit and is believed to be a former regular satellite that was scattered to its current orbit through gravitational interactions during Triton's capture. Water ice has been spectroscopically detected on its surface. Early measurements of Nereid showed large, irregular variations in its visible magnitude, which were speculated to be caused by forced precession or chaotic rotation combined with an elongated shape and bright or dark spots on the surface. This was disproved in 2016, when observations from the Kepler space telescope showed only minor variations. Thermal modeling based on infrared observations from the Spitzer and Herschel space telescopes suggest that"
"are Jupiter's Galilean moons (Ganymede, Callisto, Io, and Europa), Saturn's moon Titan, Earth's moon, and Neptune's captured natural satellite Triton. Triton, the smallest of these, has more mass than all smaller natural satellites together. Similarly in the next size group of nine natural satellites, between 1,000 km and 1,600 km across, Titania, Oberon, Rhea, Iapetus, Charon, Ariel, Umbriel, Dione, and Tethys, the smallest, Tethys, has more mass than all smaller natural satellites together. As well as the natural satellites of the various planets, there are also over 80 known natural satellites of the dwarf planets, minor planets and other small"
"from one play, ""The Tempest""; but with Margaret being named from ""Much Ado About Nothing"" that trend has ended. The one known moon (at the time) of Neptune was not named for many decades. Although the name Triton was suggested in 1880 by Camille Flammarion, it did not come into general use until the mid 20th-century, and for many years was considered ""unofficial"". In the astronomical literature it was simply referred to as ""the satellite of Neptune"". Later, the second known moon, Nereid, was named by its discoverer in 1949, Gerard P. Kuiper, soon after its discovery. Current IAU practice"
"likely produce a spectacular sight. Neptune's large outer satellite, Nereid, is not large enough to appear as a disk from Neptune, and is not noticeable in the sky, as its brightness at full phase varies from magnitude 2.2–6.4, depending on which point in its eccentric orbit it happens to be. The other irregular outer moons would not be visible to the naked eye, although a dedicated telescopic observer could potentially spot some at full phase. As with Uranus, the low light levels cause the major moons to appear very dim. The brightness of Triton at full phase is only −7.11,"
"into a synchronous rotation, and it is slowly spiralling inward because of tidal acceleration. It will eventually be torn apart, in about 3.6 billion years, when it reaches the Roche limit. In 1989, Triton was the coldest object that had yet been measured in the Solar System, with estimated temperatures of . Neptune's second known satellite (by order of discovery), the irregular moon Nereid, has one of the most eccentric orbits of any satellite in the Solar System. The eccentricity of 0.7512 gives it an apoapsis that is seven times its periapsis distance from Neptune. From July to September 1989,"
"color, almost like soot. Nereid, though discovered in 1949, still has very little known about it. Triton was revealed as having a remarkably active past. Active geysers and polar caps were discovered and a very thin atmosphere as well, with thin clouds of what is thought to be nitrogen ice particles. At just , it is the coldest known planetary body in the Solar System. The closest approach to Triton was about and it was the last solid world that ""Voyager 2"" explored close-by. Currently there are no approved future missions to visit the Neptunian system. NASA, ESA and independent"
"Nereid is only moderately elongated which disfavours forced precession of the rotation. The thermal model also indicates that the surface roughness of Nereid is very high, likely similar to the Saturnian moon Hyperion. Among the remaining irregular moons, Sao and Laomedeia follow prograde orbits, whereas Halimede, Psamathe and Neso follow retrograde orbits. Given the similarity of their orbits, it was suggested that Neso and Psamathe could have a common origin in the break-up of a larger moon. Psamathe and Neso have the largest orbits of any natural satellites discovered in the Solar system to date. They take 25 years to"
"is the most lopsided of the satellite systems of the giant planets in the Solar System. One moon, Triton, makes up nearly all of the mass of the system, with all other moons together comprising only one third of one percent. This is similar to the moon system of Saturn, where Titan makes up more than 95% of the total mass, but is different from the more balanced systems of Jupiter and Uranus. The reason for the lopsidedness of the present Neptunian system is that Triton was captured well after the formation of Neptune's original satellite system, much of which"
"(assuming an albedo of 0.04) and appears neutral (grey) in the visible light. Given the very similar colour of the satellite to that of Nereid together with the high probability (41%) of collision in the past lifespan of the Solar System, it has been suggested that the satellite could be a fragment of Nereid. Halimede, like many of the outer satellites of Neptune, is named after one of the Nereids, the fifty daughters of Nereus and Doris. Before the announcement of its name on February 3, 2007 (IAUC 8802), Halimede was known by the provisional designation S/2002 N 1. Halimede"
"only low-amplitude variations (0.033 magnitudes). Thermal modeling based on infrared observations from the Spitzer and Herschel space telescopes suggest that Nereid is only moderately elongated which disfavors forced precession of the rotation. The thermal model also indicates that the surface roughness of Nereid is very high, likely similar to the Saturnian moon Hyperion. Spectrally, Nereid appears neutral in colour and water ice has been detected on its surface. Its spectrum appears to be intermediate between Uranus's moons Titania and Umbriel, which suggests that Nereid's surface is composed of a mixture of water ice and some spectrally neutral material. The spectrum"
"moon Triton to be investigated around 2029. The proposed ""New Horizons 2"" mission (which was later scrapped) might also have done a close flyby of the Neptunian system. Neptune Neptune is the eighth and farthest known planet from the Sun in the Solar System. In the Solar System, it is the fourth-largest planet by diameter, the third-most-massive planet, and the densest giant planet. Neptune is 17 times the mass of Earth and is slightly more massive than its near-twin Uranus, which is 15 times the mass of Earth and slightly larger than Neptune. Neptune orbits the Sun once every 164.8"
"inclined relative to Neptune's equator, which suggests that it did not form in orbit around Neptune but was instead gravitationally captured by it. The next-largest irregular satellite in the Solar System, Saturn's moon Phoebe, has only 0.03% of Triton's mass. The capture of Triton, probably occurring some time after Neptune formed a satellite system, was a catastrophic event for Neptune's original satellites, disrupting their orbits so that they collided to form a rubble disc. Triton is massive enough to have achieved hydrostatic equilibrium and to retain a thin atmosphere capable of forming clouds and hazes. Inward of Triton are seven"
"several lines of evidence, including binaries being very common among the large Kuiper belt objects. The event was brief but gentle, saving Triton from collisional disruption. Events like this may have been common during the formation of Neptune, or later when it migrated outward. However, simulations in 2017 showed that after Triton's capture and before its orbital eccentricity decreased it probably did collide with at least one other moon, and caused collisions between other moons. Triton is the seventh-largest moon and sixteenth-largest object in the Solar System, and is modestly larger than the dwarf planets Pluto and Eris. It comprises"
"on the structure of the Kuiper belt. Neptune has 14 known moons. Triton is the largest Neptunian moon, comprising more than 99.5% of the mass in orbit around Neptune, and it is the only one massive enough to be spheroidal. Triton was discovered by William Lassell just 17 days after the discovery of Neptune itself. Unlike all other large planetary moons in the Solar System, Triton has a retrograde orbit, indicating that it was captured rather than forming in place; it was probably once a dwarf planet in the Kuiper belt. It is close enough to Neptune to be locked"
"close to their giant-planet primaries. (This mechanism would have also operated on Triton in the past, before its orbit was circularized.) Many other natural satellites, such as Earth's Moon, Ganymede, Tethys and Miranda, show evidence of past geological activity, resulting from energy sources such as the decay of their primordial radioisotopes, greater past orbital eccentricities (due in some cases to past orbital resonances), or the differentiation or freezing of their interiors. Enceladus and Triton both have active features resembling geysers, although in the case of Triton solar heating appears to provide the energy. Titan and Triton have significant atmospheres; Titan"
"or whether some may include small solid objects (moons). Uranus has by far the most extensive system of inner satellites, containing thirteen known moons: Neptune has seven known inner satellites: It is thought that they are rubble piles re-accreted from fragments of Neptune's original satellites (inner or not). These were strongly perturbed by Triton in the period soon after that moon's capture into a very eccentric initial orbit. The perturbations led to collisions between the satellites, and that portion of the fragments that were not lost re-accreted into the present inner satellites after Triton's orbit became circularised. Most of the"
"discovery; he later successfully suggested the name Hyperion, previously chosen by John Herschel, for the eighth moon of Saturn when he discovered it. Triton is unique among all large moons in the Solar System for its retrograde orbit around its planet (i.e. it orbits in a direction opposite to the planet's rotation). Most of the outer irregular moons of Jupiter and Saturn also have retrograde orbits, as do some of Uranus's outer moons. However, these moons are all much more distant from their primaries, and are small in comparison; the largest of them (Phoebe) has only 8% of the diameter"
"contributing to a tenuous nitrogen atmosphere less than 1/70,000 the pressure of Earth's atmosphere at sea level. It is the second-largest planetary moon in relation to its primary, after Earth's moon. Triton was discovered by British astronomer William Lassell on October 10, 1846, just 17 days after the discovery of Neptune. He discovered Triton with his self-built, 61 cm telescope. A brewer by trade, Lassell began making mirrors for his amateur telescope in 1820. When John Herschel received news of Neptune's discovery, he wrote to Lassell suggesting he search for possible moons. Lassell did so and discovered Triton eight days"
"as their orbits are analogous to the trojan asteroids of Jupiter. The trojan moons are Telesto and Calypso, which are the leading and following companions, respectively, of the Saturnian moon Tethys; and Helene and Polydeuces, the leading and following companions of the Saturnian moon Dione. The discovery of 243 Ida's natural satellite Dactyl in the early 1990s confirmed that some asteroids have natural satellites; indeed, 87 Sylvia has two. Some, such as 90 Antiope, are double asteroids with two comparably sized components. Neptune's moon Proteus is the largest irregularly shaped natural satellite. All other known natural satellites that are at"
"due to its dimness. Triton did not have an official name until the twentieth century. The name ""Triton"" was suggested by Camille Flammarion in his 1880 book ""Astronomie Populaire"", but it did not come into common use until at least the 1930s. Until this time it was usually simply known as ""the satellite of Neptune"". Other moons of Neptune are also named for Greek and Roman water gods, in keeping with Neptune's position as god of the sea: either from Greek mythology, usually children of Poseidon, the Greek Neptune (Triton, Proteus, Despina, Thalassa); lovers of Poseidon (Larissa); classes of minor"
"a result of tidal stresses from Neptune. Proteus, like the other inner satellites of Neptune, is unlikely to be an original body that formed with it, and is more likely to have accreted from the rubble that was produced after Triton's capture. Triton's orbit upon capture would have been highly eccentric, and would have caused chaotic perturbations in the orbits of the original inner Neptunian satellites, causing them to collide and reduce to a disc of rubble. Only after Triton's orbit became circularised did some of the rubble disc re-accrete into the present-day satellites. Proteus (moon) Proteus ( ; Greek:"
"fifty."" Nereid In Greek mythology, the Nereids ( ; ""Nereides"", sg. ""Nereis"") are sea nymphs (female spirits of sea waters), the 50 daughters of Nereus and Doris, sisters to Nerites. They often accompany Poseidon, the god of the sea, and can be friendly and helpful to sailors, like the Argonauts in their search for the Golden Fleece. Nereids are particularly associated with the Aegean Sea, where they dwelt with their father Nereus in the depths within a golden palace. The most notable of them are Thetis, wife of Peleus and mother of Achilles; Amphitrite, wife of Poseidon; and Galatea, the"
"Naiad (moon) Naiad ( or ; ), also known as Neptune III, is the innermost satellite of Neptune, named after the Naiads of Greek legend. Naiad was discovered sometime before mid-September 1989 from the images taken by the ""Voyager 2"" probe. The last moon to be discovered during the flyby, it was designated S/1989 N 6. The discovery was announced on September 29, 1989, in the IAU Circular No. 4867, but the text only talks of ""25 frames taken over 11 days"", giving a discovery date of sometime before September 18. The name was given on 16 September 1991. Naiad"
"Nereid In Greek mythology, the Nereids ( ; ""Nereides"", sg. ""Nereis"") are sea nymphs (female spirits of sea waters), the 50 daughters of Nereus and Doris, sisters to Nerites. They often accompany Poseidon, the god of the sea, and can be friendly and helpful to sailors, like the Argonauts in their search for the Golden Fleece. Nereids are particularly associated with the Aegean Sea, where they dwelt with their father Nereus in the depths within a golden palace. The most notable of them are Thetis, wife of Peleus and mother of Achilles; Amphitrite, wife of Poseidon; and Galatea, the vain"
"that are more massive than Eris are the Moon, the four Galilean moons of Jupiter (Io, Europa, Ganymede, and Callisto), one moon of Saturn (Titan), and one moon of Neptune (Triton). The others are six moons of Saturn (Mimas, Enceladus, Tethys, Dione, Rhea, and Iapetus), five moons of Uranus (Miranda, Ariel, Umbriel, Titania, and Oberon), and one moon of Pluto (Charon). There are additional possibilities among TNOs, including Dysnomia orbiting Eris. Alan Stern calls these moons ""satellite planets"", one of three categories of planet together with dwarf planets and classical planets. The term ""planemo"" (""planetary-mass object"") covers all three. In"
"Unlike Mab and Perdita, Uranian satellites also discovered in 2003, it does not seem to be perturbed. Following its discovery, Cupid was given the temporary designation S/2003 U 2. It is also designated Uranus XXVII. It should not be confused with the asteroid 763 Cupido. Cupid (moon) Cupid ( ) is an inner satellite of Uranus. It was discovered by Mark R. Showalter and Jack J. Lissauer in 2003 using the Hubble Space Telescope. It was named after a character in William Shakespeare's play ""Timon of Athens"". It is the smallest of inner Uranian satellites, crudely estimated to be only"
"Norse mythology. Greip (moon) Greip ( ), or Saturn LI (provisional designation S/2006 S 4), is a natural satellite of Saturn. Its discovery was announced by Scott S. Sheppard, David C. Jewitt, Jan Kleyna, and Brian G. Marsden on 26 June 2006, from observations taken between 5 January and 1 May 2006. Greip is about 6 kilometres in diameter, and orbits Saturn at an average distance of 18,066 Mm in 906.556 days, at an inclination of 172.7° to the ecliptic (159.2° to Saturn's equator), in a retrograde direction and with an eccentricity of 0.3735. It is named after Greip, a"
"carried out by the Infrared Astronomical Satellite IRAS, the Japanese Akari satellite and the NEOWISE mission of NASA's WISE telescope, ""Merope"" measures between 60.439 and 74.36 kilometers in diameter and its surface has an albedo between 0.03 and 0.053. The ""Collaborative Asteroid Lightcurve Link"" derives an albedo of 0.0358 and a diameter of 67.11 kilometers based on an absolute magnitude of 10.1. This minor planet was named after the nymph Merope from Greek mythology. She is one of the seven Pleiades, daughters of the Titan Atlas and the sea-nymph Pleione (). Merope is also a bright star in the constellation"
"oxygen and sulfur from the tenuous atmosphere of Jupiter's volcanic moon, Io and other objects including Jupiter and Europa. A torus of oxygen and hydrogen produced by Saturn's moon, Enceladus forms part of the E ring around Saturn. Nitrogen gas transfer between Pluto and Charon has also been modelled and is expected to be observable by the New Horizons space probe. Similar tori produced by Saturn's moon Titan (nitrogen) and Neptune's moon Triton (hydrogen) is predicted. Complex magnetic interactions have been observed in satellite systems. Most notably, the interaction of Jupiter's strong magnetic field with those of Ganymede and Io."
"critical point. Recent simulations of planetary migration have suggested that both ice giants formed closer to the Sun than their present positions, and moved outwards after formation (the Nice model). Uranus has 27 known natural satellites. The names of these satellites are chosen from characters in the works of Shakespeare and Alexander Pope. The five main satellites are Miranda, Ariel, Umbriel, Titania, and Oberon. The Uranian satellite system is the least massive among those of the giant planets; the combined mass of the five major satellites would be less than half that of Triton (largest moon of Neptune) alone. The"