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 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 roughly 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 gases and volatile material such as liquid water, ammonia, and hydrocarbons. The erupted material is collectively referred to as cryolava; it originates from a reservoir of subsurface cryomagma. Cryovolcanic eruptions can take many forms, such as fissure and curtain eruptions, effusive cryolava flows, and large-scale resurfacing, and can vary greatly in output volumes. Immediately after an eruption, cryolava quickly freezes, constructing geological features and altering the surface.
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.
Planum Australe is the southern polar plain on Mars. It extends southward of roughly 75°S and is centered at 83.9°S 160.0°E. The geology of this region was to be explored by the failed NASA mission Mars Polar Lander, which lost contact on entry into the Martian atmosphere.
The geology of Mars is the scientific study of the surface, crust, and interior of the planet Mars. It emphasizes the composition, structure, history, and physical processes that shape the planet. It is analogous to the field of terrestrial geology. In planetary science, the term geology is used in its broadest sense to mean the study of the solid parts of planets and moons. The term incorporates aspects of geophysics, geochemistry, mineralogy, geodesy, and cartography. A neologism, areology, from the Greek word Arēs (Mars), sometimes appears as a synonym for Mars's geology in the popular media and works of science fiction. The term areology is also used by the Areological Society.
Melas Chasma is a canyon on Mars, the widest segment of the Valles Marineris canyon system, located east of Ius Chasma at 9.8°S, 283.6°E in Coprates quadrangle. It cuts through layered deposits that are thought to be sediments from an old lake that resulted from runoff of the valley networks to the west. Other theories include windblown sediment deposits and volcanic ash. Support for abundant, past water in Melas Chasma is the discovery by MRO of hydrated sulfates. In addition, sulfate and iron oxides were found by the same satellite. Although not chosen as one of the finalists, it was one of eight potential landing sites for the Mars 2020 rover, a mission with a focus on astrobiology.
Rain and snow was a regular occurrence on Mars in the past; especially in the Noachian and early Hesperian epochs. Water was theorized to seep into the ground until it reached a formation that would not allow it to penetrate further. Water then accumulated forming a saturated layer. Deep aquifers may still exist.
In summer 1965, the first close-up images from Mars showed a cratered desert with no signs of water. However, over the decades, as more parts of the planet were imaged with better cameras on more sophisticated satellites, Mars showed evidence of past river valleys, lakes and present ice in glaciers and in the ground. It was discovered that the climate of Mars displays huge changes over geologic time because its axis is not stabilized by a large moon, as Earth's is. Also, some researchers maintain that surface liquid water could have existed for periods of time due to geothermal effects, chemical composition or asteroid impacts. This article describes some of the places that could have held large lakes.
The geology of Charon encompasses the characteristics of the surface, crust, and interior of Pluto's moon Charon. Like the geology of Pluto, almost nothing was known of Charon's geology until the New Horizons of the Pluto system on 14 July 2015. 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.
Vulcan Planum, or Vulcan Planitia, is the unofficial name given to a large plain on the southern hemisphere of Pluto's moon Charon. It 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 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 media franchise Star Trek. 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.
Nasreddin is a crater on Pluto's largest moon, Charon. The crater was first observed by NASA's New Horizons space probe on its flyby of Pluto in 2015. The name was chosen as a reference to Nasreddin, the hero of humorous folktales told throughout the Middle East, Southern Europe, and parts of Asia.
Mandjet Chasma is a chasma on Pluto's moon, Charon. Mandjet Chasma is 385 km (239 mi) long, and about 5–7 km (3.1–4.3 mi) deep with an average width of 30 km (19 mi). The chasma is part of a global tectonic belt: a series of canyons, scarps, and troughs that traverse the face of Charon along the northern edge of Vulcan Planum. The feature was discovered using stereoscopic processing of New Horizons images.
Serenity Chasma is the unofficial name given to a large pull-apart fault on Pluto's moon, Charon. It is part of a series of faults that run along the perimeter of Vulcan Planum. It was discovered by the New Horizons mission, and informally named after the fictitious spaceship, Serenity.
The climate of Pluto concerns the atmospheric dynamics, weather, and long-term trends on the dwarf planet Pluto. Five climate zones are assigned on the dwarf planet: tropics, arctic, tropical arctic, diurnal, and polar. These climate zones are delineated based on astronomically defined boundaries or sub-solar latitudes, which are not associated with the atmospheric circulations on the dwarf planet. Charon, the largest moon of Pluto, is tidally locked with it, and thus has the same climate zone structure as Pluto itself.
Caleuche Chasma is a Y-shaped chasma on Pluto's moon, Charon. Caleuche Chasma is 400 km (250 mi) long. The feature was discovered using stereoscopic processing of New Horizons images. At approximately 13 km (8.1 mi) deep, it is the deepest known feature on the natural satellite, and one of the deepest known canyons in the Solar System.
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.
