"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"
"Organa (crater) Organa is the informal name given to a crater on Pluto's largest moon, Charon. The crater was discovered by NASA's ""New Horizons"" space probe on its flyby of Pluto. The name was chosen as a reference to Leia Organa from the ""Star Wars"" media franchise in the theme of naming Charon's craters after science fiction characters. Organa crater is rich in frozen ammonia, which suggests it was created very recently. The location of Organa crater is in the northern Pluto-facing hemisphere of Charon. Organa crater is the only known crater on Charon that contains abundant ammonia. The ammonia"
"proportionately largest moon Charon, is also the site of many eclipses. A series of such mutual eclipses occurred between 1985 and 1990. These daily events led to the first accurate measurements of the physical parameters of both objects. Eclipses are impossible on Mercury and Venus, which have no moons. However, both have been observed to transit across the face of the Sun. There are on average 13 transits of Mercury each century. Transits of Venus occur in pairs separated by an interval of eight years, but each pair of events happen less than once a century. According to NASA, the"
"10199 Chariklo 10199 Chariklo ( or ; ; provisional designation ) is the largest confirmed centaur (minor planet of the outer Solar System). It orbits the Sun between Saturn and Uranus, grazing the orbit of Uranus. On 26 March 2014, astronomers announced the discovery of two rings (nicknamed Oiapoque and Chuí) around Chariklo by observing a stellar occultation, making it the first minor planet known to have rings. Chariklo was discovered by James V. Scotti of the Spacewatch program on February 15, 1997. Chariklo is named after the nymph Chariclo (""""), the wife of Chiron and the daughter of Apollo."
"of the earlier craters. In 2018,the International Astronomical Union named one crater on Charon, as Revati who is a character in the Hindu epic Mahabharata. Charon has a series of extensive grabens or canyons, such as Serenity Chasma, which extend as an equatorial belt for at least . Argo Chasma potentially reaches as deep as , with steep cliffs that may rival Verona Rupes on Miranda for the title of tallest cliff in the solar system. In a released photo by ""New Horizons"", an unusual surface feature has captivated and baffled the scientist team of the mission. The image reveals"
"of a tidal lock. Charon is a relatively large moon in comparison to its primary and also has a very close orbit. This results in Pluto and Charon being mutually tidally locked. Pluto's other moons are not tidally locked; Styx, Nix, Kerberos, and Hydra all rotate chaotically due to the influence of Charon. The tidal locking situation for asteroid moons is largely unknown, but closely orbiting binaries are expected to be tidally locked, as well as contact binaries. The Moon's rotation and orbital periods are tidally locked with each other, so no matter when the Moon is observed from Earth"
"Charon. It was only later that he found the same name in mythology, that being the ferryman who carried souls across the Acheron River, one of the five mythical rivers that surrounded Pluto's underworld. James W. Christy James Walter ""Jim"" Christy (born September 15, 1938) is an American astronomer. Christy was born in 1938 in Milwaukee, Wisconsin. He attended the University of Arizona and earned a Bachelor of Science degree in astronomy from there in 1965. On June 22, 1978 while working at the United States Naval Observatory, he discovered that Pluto had a moon, which he named Charon shortly"
"in size of Charon and Pluto has prompted some astronomers to call it a double dwarf planet. The system is also unusual among planetary systems in that each is tidally locked to the other, which means that Pluto and Charon always have the same hemisphere facing each other. From any position on either body, the other is always at the same position in the sky, or always obscured. This also means that the rotation period of each is equal to the time it takes the entire system to rotate around its barycenter. In 2007, observations by the Gemini Observatory of"
"while searching for Plutonian rings. Styx, announced on 7 July 2012, was discovered while looking for potential hazards for ""New Horizons"". Charon is about half the diameter of Pluto and is so massive (nearly one eighth of the mass of Pluto) that the system's barycenter lies between them, approximately 960 km above Pluto's surface. Charon and Pluto are also tidally locked, so that they always present the same face toward each other. The IAU General Assembly in August 2006 considered a proposal that Pluto and Charon be reclassified as a double planet, but the proposal was abandoned. Pluto's four small"
"of active cryogeysers. Mutual eclipses of Pluto and Charon in the 1980s allowed astronomers to take spectra of Pluto and then the combined spectrum of the pair. By subtracting Pluto's spectrum from the total, astronomers were able to spectroscopically determine the surface composition of Charon. The northern regions of Charon are composed partially of hydrocarbons and tholins, whereas the lower latitudes are more diverse in composition. Charon also appears to have little, if any, atmosphere. Photometric mapping of Charon's surface shows a latitudinal trend in albedo, with a bright equator band and darker poles. The south polar region is apparently"
"for newly discovered Neptunian moons is to accord with these first two choices by naming them after Greek sea deities. Neptune XIV, the most recently discovered Neptunian moon, was given a Roman numeral but not a name. The name of Pluto's moon Charon was suggested by James W. Christy, its discoverer, soon after its discovery. The other four moons are named Hydra, Nix, Kerberos, and Styx. Charon, Hydra, Nix, and Kerberos are all characters in Greek mythology, with ties to Hades (the Greek equivalent of Pluto). Charon ferries the dead across the River Acheron, Hydra guards the waters of the"
"its largest. However, Kerberos, although slightly larger, cannot make total eclipses as its largest minor axis is a mere 32 arcseconds. Eclipses by Kerberos and Styx will entirely consist of partial and hybrid eclipses, with total eclipses being extremely rare. The next period of mutual events due to Charon will begin in October 2103, peak in 2110, and end in January 2117. During this period, solar eclipses will occur once each Plutonian day, with a maximum duration of 90 minutes. The Pluto system was visited by the ""New Horizons"" spacecraft in July 2015. Images with resolutions of up to 330"
"meters per pixel were returned of Nix and up to 1.1 kilometers per pixel of Hydra. Lower-resolution images were returned of Styx and Kerberos. Author Edmond Hamilton referred to three moons of Pluto in his 1940 novel ""Calling Captain Future"", naming them , , and . Charon was listed as the largest of them. All three moons would not be discovered until the year 1970, according to Hamilton. The real Charon was discovered in 1978. Moons of Pluto The dwarf planet Pluto has five moons down to a detection limit of about 1 km in diameter. In order of distance"
"concluded that the bulge was indeed a moon. The photographic evidence was considered convincing but not conclusive (it remained possible that the bulge was due to Pluto having an unexpectedly irregular shape). However, based on Charon's calculated orbit, a series of mutual eclipses of Pluto and Charon was predicted and observed, confirming the discovery. In more modern telescopes, such as the Hubble or ground-based telescopes using adaptive optics, separate images of Pluto and Charon can be resolved, and the ""New Horizons"" probe took images showing some of Charon's surface features. In late 2008, the asteroid 129564 Christy was named in"
"in Pluto's orbit; coincidentally, these points are near Pluto's perihelion and aphelion. Occultations occur when Pluto passes in front of and blocks one of Pluto's satellites. Charon has an angular diameter of 4 degrees of arc as seen from the surface of Pluto; the Sun appears much smaller, only 39 to 65 arcseconds. Charon's proximity further ensures that a large proportion of Pluto's surface can experience an eclipse. Because Pluto always presents the same face towards Charon due to tidal locking, only the Charon-facing hemisphere experiences solar eclipses by Charon. The smaller moons can cast shadows elsewhere. The angular diameters"
"of , subsequently revised downward, which at the time of discovery in 2002 made it the largest object found in the Solar System since the discovery of Pluto. Quaoar was later supplanted by , , , and , though Sedna was later found to be somewhat smaller than Quaoar. Quaoar is about as massive as (if somewhat smaller than) Pluto's moon Charon, which is approximately times as massive as . Quaoar is roughly one twelfth the diameter of Earth, one third the diameter of the Moon, and half the size of Pluto. Quaoar was the first trans-Neptunian object to be"
"dark, and was imaged by New Horizons using light reflected off Pluto (Plutolight). Charon's volume and mass allow calculation of its density, , which is slightly lower than Pluto's and hence Charon has a slightly lower proportion of rock in its interior relative to Pluto. This difference is not as large as those of many other collisional satellites. Prior to ""New Horizons"", there were two conflicting theories about Charon's internal structure: some scientists thought it to be a differentiated body like Pluto, with a rocky core and an icy mantle, whereas others thought it would be uniform throughout. Evidence in"
"its surface, though observations by ""New Horizons"" have revealed Pluto's upper atmosphere to be far colder than expected (70 K, as opposed to about 100 K). Pluto's atmosphere is divided into roughly 20 regularly spaced haze layers up to 150 km high, thought to be the result of pressure waves created by airflow across Pluto's mountains. Pluto has five known natural satellites. The closest to Pluto is Charon. First identified in 1978 by astronomer James Christy, Charon is the only moon of Pluto in hydrostatic equilibrium; Charon's mass is sufficient to cause the barycenter of the Pluto–Charon system to be"
"coastal borders of Brazil. A request for formal names will be submitted to the IAU at a later date. It has been speculated that 2060 Chiron may have a similar pair of rings. 10199 Chariklo 10199 Chariklo ( or ; ; provisional designation ) is the largest confirmed centaur (minor planet of the outer Solar System). It orbits the Sun between Saturn and Uranus, grazing the orbit of Uranus. On 26 March 2014, astronomers announced the discovery of two rings (nicknamed Oiapoque and Chuí) around Chariklo by observing a stellar occultation, making it the first minor planet known to have"
"earlier craters. Charon's surface contains several large canyons from 5 to 10 km deep. These are northeast-southwest trending. One system of troughs and cliffs extends for 1050 km. One such graben is Serenity Chasma which is 60 km wide. Others include Macross Chasma which lined up with Serenity Chasma forms a belt which extends 1050 km, also Tardis Chasma, Nostromo Chasma, and Argo Chasma which is 5 km deep. Charon's north polar region is considerably darker and more reddish than the rest of its surface. The favored explanation for this phenomenon is that they are formed by condensation of gases"
"darker than the north. The north polar region is dominated by a very large dark area informally dubbed ""Mordor"" by the ""New Horizons"" team. The Mordor Macula is distinctly red. Aside from Mordor, however, ""New Horizons"" imaged unexpectedly few other impact craters on Charon and found a youthful surface, indicating that Charon is probably geologically active. In particular, the southern hemisphere has fewer craters than the northern and is considerably less rugged, suggesting that a massive resurfacing event—perhaps prompted by the partial or complete freezing of an internal ocean—occurred at some point in the past and removed many of the"
"(compared to 1 ""g"" for Earth). The discovery of Pluto's satellite Charon in 1978 enabled a determination of the mass of the Pluto–Charon system by application of Newton's formulation of Kepler's third law. Observations of Pluto in occultation with Charon allowed scientists to establish Pluto's diameter more accurately, whereas the invention of adaptive optics allowed them to determine its shape more accurately. With less than 0.2 lunar masses, Pluto is much less massive than the terrestrial planets, and also less massive than seven moons: Ganymede, Titan, Callisto, Io, the Moon, Europa, and Triton. The mass is much less than thought"
"rings were discovered by ""New Horizons"", ruling out any more moons of significant size orbiting Pluto. Pluto's moons are listed here by orbital period, from shortest to longest. Charon, which is massive enough to have collapsed into a spheroid at some point in its history, is highlighted in light purple. Pluto has been added for comparison. Transits occur when one of Pluto's moons passes between Pluto and the Sun. This occurs when one of the satellites' orbital nodes (the points where their orbits cross Pluto's ecliptic) lines up with Pluto and the Sun. This can only occur at two points"
"a minor planet and a comet, and is accordingly also known by the cometary designation ""95P/Chiron"". Chiron is named after the centaur Chiron in Greek mythology. Michael Brown lists it as possibly a dwarf planet with a measured diameter of 206 km (128 miles) which is near the lower limit for an icy dwarf planet (around 200 km, or 124 miles). Chiron was discovered on 1 November 1977 by Charles Kowal from images taken on 18 October at Palomar Observatory. It was given the temporary designation of . It was found near aphelion and at the time of discovery it"
"2060 Chiron 2060 Chiron (), provisional designation , and also known as 95P/Chiron, is a small solar system body (or minor planet) in the outer Solar System, orbiting the Sun between Saturn and Uranus. Discovered in 1977 by Charles Kowal, it was the first-identified member of a new class of objects now known as centaurs—bodies orbiting between the asteroid belt and the Kuiper belt. Although it was initially called an asteroid and classified only as a minor planet with the designation ""2060 Chiron"", it was later found to exhibit behavior typical of a comet. Today it is classified as both"
"13) in its solar system, with a solar orbit of 350 days. Five moons orbit Kulthea. Orhan is the largest (it can be seen in full daylight) and circles Kulthea in 70 days. This moon is very important to peoples and cultures of Kulthea, and is home to the Lords of Orhan. Many calendrical systems are based on Orhan's movement through the sky. Varin is the second largest moon, and is orange in color. With its polar orbit and red color, Charon, the third moon and home to the Dark Gods, is greatly feared. The waxing of Charon, as well"
"Oberon (moon) Oberon, also designated , is the outermost major moon of the planet Uranus. It is the second-largest and second most massive of the Uranian moons, and the ninth most massive moon in the Solar System. Discovered by William Herschel in 1787, Oberon is named after the mythical king of the fairies who appears as a character in Shakespeare's ""A Midsummer Night's Dream"". Its orbit lies partially outside Uranus's magnetosphere. It is likely that Oberon formed from the accretion disk that surrounded Uranus just after the planet's formation. The moon consists of approximately equal amounts of ice and rock,"
"ranges from 30 to 49 astronomical units or AU (4.4–7.4 billion km) from the Sun. This means that Pluto periodically comes closer to the Sun than Neptune, but a stable orbital resonance with Neptune prevents them from colliding. Light from the Sun takes about 5.5 hours to reach Pluto at its average distance (39.5 AU). Pluto has five known moons: Charon (the largest, with a diameter just over half that of Pluto), Styx, Nix, Kerberos, and Hydra. Pluto and Charon are sometimes considered a binary system because the barycenter of their orbits does not lie within either body. On July"
"the dwarf planet Pluto and its satellite Charon. They have already reached a state where Charon is only visible from one hemisphere of Pluto and vice versa. For orbits that do not have an eccentricity close to zero, the rotation rate tends to become locked with the orbital speed when the body is at periapsis, which is the point of strongest tidal interaction between the two objects. If the orbiting object has a companion, this third body can cause the rotation rate of the parent object to vary in an oscillatory manner. This interaction can also drive an increase in"
"Sharrkan (crater) Sharrkan is an impact crater in the northern hemisphere of Saturn's moon Enceladus. Sharrkan was first observed in ""Cassini"" images during that mission's February 2005 flyby of Enceladus. It is located at 16.4° North Latitude, 298.3° West Longitude. At only 3.6 kilometers across, Sharrkan is the smallest named crater on Enceladus, though numerous, smaller, unnamed craters have been observed. The crater has a basic bowl-shape typical of small, simple craters. Sharrkan is named after one of the sons of King Omar in ""The Tale of King Omar and his Sons"" in ""The Book of One Thousand and One"
"antimonide) camera, ""Astrocam"". In 1978, the 1.55-m telescope was used to ""discover the moon of dwarf planet Pluto, named 'Charon'"". (Pluto itself was discovered in 1930, across town at Lowell Observatory). The Charon discovery led to mass calculations which ultimately revealed how tiny Pluto was, and eventually caused the IAU to reclassify Pluto as a dwarf (not a principle) planet. The 1.55-meter telescope was also used to observe and track NASA's Deep Impact Spacecraft, as it navigated to a successful inter-planetary impact with the celebrated Comet 9p/Tempel, in 2005. This telescope is particularly well-suited to perform stellar parallax studies, narrow-field"
"this collision, rather than being captured Kuiper Belt objects. This and their near orbital resonances with Charon (see below) suggest that they formed closer to Pluto than they are at present and migrated outward as Charon reached its current orbit. Their grey color is different from that of Pluto, one of the reddest bodies in the Solar System. This is thought to be due to a loss of volatiles during the impact or subsequent coalescence, leaving the surfaces of the moons dominated by water ice. However, such an impact should have created additional debris (more moons), yet no moons or"
"P. Hogan's 1982 space opera novel ""Voyage from Yesteryear"", in which a human colony is artificially planted by an automatic probe on a planet later named by colonists as Chiron. In the game, Chiron has two moons, named after the centaurs Nessus and Pholus, with the combined tidal force of Earth's Moon, and is the second planet out from Alpha Centauri A, the innermost planet being the Mercury-like planet named after the centaur Eurytion. Alpha Centauri B is also dubbed Hercules, a reference to him killing several centaurs in mythology, and the second star preventing the formation of larger planets."