Triton is the largest natural satellite of the planet Neptune, and was the first Neptunian moon to be discovered, on October 11, 1846, by English astronomer William Lassell. It is the only large moon in the Solar System with a retrograde orbit, an orbit in the direction opposite to its planet's rotation. Because of its retrograde orbit and composition similar to Pluto, Triton is thought to have been a dwarf planet, captured from the Kuiper belt.
Pluto is a dwarf planet in the Kuiper belt, a ring of bodies beyond the orbit of Neptune. It is the ninth-largest and tenth-most-massive known object to directly orbit the Sun. It is the largest known trans-Neptunian object by volume, by a small margin, but is slightly less massive than Eris. Like other Kuiper belt objects, Pluto is made primarily of ice and rock and is much smaller than the inner planets. Pluto has only one sixth the mass of Earth's moon, and one third its volume.
Charon, known as (134340) Pluto I, is the largest of the five known natural satellites of the dwarf planet Pluto. It has a mean radius of 606 km (377 mi). Charon is the sixth-largest known trans-Neptunian object after Pluto, Eris, Haumea, Makemake and Gonggong. It was discovered in 1978 at the United States Naval Observatory in Washington, D.C., using photographic plates taken at the United States Naval Observatory Flagstaff Station (NOFS).
A cryovolcano is a type of volcano that erupts volatiles such as water, ammonia or methane into an extremely cold environment that is at or below their freezing point. The process of formation is known as cryovolcanism. Collectively referred to as cryomagma, cryolava or ice-volcanic melt, these substances are usually liquids and can form plumes, but can also be in vapour form. After the eruption, cryomagma is expected to condense to a solid form when exposed to the very low surrounding temperature. Cryovolcanoes may potentially form on icy moons and other objects with abundant water past the Solar System's snow line. A number of features have been identified as possible cryovolcanoes on Pluto, Titan and Ceres, and a subset of domes on Europa may have cryovolcanic origins. In addition, although they are not known to form volcanoes, ice geysers have been observed on Enceladus and potentially Triton.
The geology of Pluto consists of the characteristics of the surface, crust, and interior of Pluto. Because of Pluto's distance from Earth, in-depth study from Earth is difficult. Many details about Pluto remained unknown until 14 July 2015, when New Horizons flew through the Pluto system and began transmitting data back to Earth. When it did, Pluto was found to have remarkable geologic diversity, with New Horizons team member Jeff Moore saying that it "is every bit as complex as that of Mars". The final New Horizons Pluto data transmission was received on 25 October 2016. In June 2020, astronomers reported evidence that Pluto may have had a subsurface ocean, and consequently may have been habitable, when it was first formed.
Nix is a natural satellite of Pluto, with a diameter of 49.8 km (30.9 mi) across its longest dimension. It was discovered along with Pluto's outermost moon Hydra on 15 May 2005 by astronomers using the Hubble Space Telescope, and was named after Nyx, the Greek goddess of the night. Nix is the third moon of Pluto by distance, orbiting between the moons Styx and Kerberos.
Nasir al-Din was an honorific title, and is an Arabic masculine given name.
The atmosphere of Pluto consists mainly of nitrogen (N2), with minor amounts of methane (CH4) and carbon monoxide (CO), all of which are vaporized from their ices on Pluto's surface. It contains layered haze, probably consisting of heavier compounds which form from these gases due to high-energy radiation. The atmosphere of Pluto is notable for its strong and not completely clear seasonal changes caused by peculiarities of the orbital and axial rotation of Pluto.
Cthulhu Macula is a prominent surface feature of the dwarf planet Pluto, that is reminiscent of a whale in shape. It is an elongated dark region along Pluto's equator, 2,990 km (1,860 mi) long and one of the darkest features on Pluto. It is west of the Sputnik Planitia region of Tombaugh Regio, also known as Pluto's "heart", and to the east of Meng-P'o, the easternmost of Pluto's "Brass Knuckles".
The geology of Charon are the characteristics of the surface, crust, and interior of Pluto's moon Charon. Charon's diameter is 1,208 km (751 mi)—just over half that of Pluto. Charon is sufficiently massive to have collapsed into a spheroid under its own gravity.
The geography of Pluto entails the delineation and characterization of regions on Pluto. Plutonian geography is mainly focused on what is called physical geography on Earth; that is, the distribution of physical features across Pluto and their cartographic representations. On 14 July 2015, the New Horizons spacecraft became the first spacecraft to fly by Pluto. During its brief flyby, New Horizons made detailed geographical measurements and observations of Pluto and its moons.
Vulcan Planum is the unofficial name given to a large plain on the surface of Pluto's moon Charon, discovered by New Horizons during its flyby of Pluto in July 2015. It is named after the fictional planet Vulcan in the science-fiction series Star Trek. The name is not approved by International Astronomical Union, as of 2020.
Kirk Crater is the unofficial name given to a small crater on Pluto's largest moon Charon. The crater was discovered by the New Horizons space probe in 2015 during its flyby of Pluto and its moons. It was named after the character James T. Kirk from the Star Trek media franchise. The crater is located in the southern hemisphere, just south of the equator, and just east of the prime meridian, near Clarke Montes, in a region that astronomers have named Vulcan Planum.
Vader is the unofficial name given to a dark crater on Pluto's largest moon Charon. The crater was discovered by NASA's New Horizons space probe on its way by Pluto. It was named after Darth Vader from the Star Wars media franchise.
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, which keeps with 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. This crater is located in the northern Pluto-facing hemisphere of Charon.
Oz Terra is the unofficial name given to a major geological region on Charon. The Pluto-facing hemisphere of Charon is divided onto two primary regions; Oz Terra in the north and Vulcan Planum in the south. These regions are separated by a series of scarps near Charon's equator. The region was discovered by New Horizons during its flyby of Pluto in July 2015.
Dorothy Crater is the largest known impact basin on Pluto's moon Charon. The crater was discovered by the New Horizons space probe in 2015 during its flyby of Pluto and its moons. It was named after Dorothy Gale from the novel The Wonderful Wizard of Oz. The crater is located near Charon's north pole, and overlaps the edge of Mordor Macula.
Deseado Crater is a large Hesperian- or Amazonian-age impact crater in Promethei Planum near the south pole of Mars, within the Mare Australe quadrangle, due south of the Hellas impact basin. It is named for Puerto Deseado, Argentina. The crater contains a central topographic high interpreted to be an ice mound of probable Amazonian age. Despite the proximity of the ice mound to the southern polar ice sheet, it is not interpreted to have initially been a part of it. Deseado Crater features in the Mass Effect trilogy as the home of a structure constructed by a species called the Protheans to study the evolution of early humans.
