A geyser is a spring characterized by an intermittent discharge of water ejected turbulently and accompanied by steam. As a fairly rare phenomenon, the formation of geysers is due to particular hydrogeological conditions that exist only in a few places on Earth.
Europa, or Jupiter II, is the smallest of the four Galilean moons orbiting Jupiter, and the sixth-closest to the planet of all the 95 known moons of Jupiter. It is also the sixth-largest moon in the Solar System. Europa was discovered independently by Simon Marius and Galileo Galilei and was named after Europa, the Phoenician mother of King Minos of Crete and lover of Zeus.
Triton is the largest natural satellite of the planet Neptune. It is the only moon of Neptune massive enough to be rounded under its own gravity, and orbits Neptune with a retrograde orbit—an orbit in the direction opposite to its planet's rotation—the only large moon in the Solar System to do so. Because of its retrograde orbit and composition similar to Pluto, Triton is thought to have been a dwarf planet, captured from the Kuiper belt. Triton hosts a thin but well-structured atmosphere, composed primarily of nitrogen and hosting a layer of clouds.
Volcanism, vulcanism, volcanicity, or volcanic activity is the phenomenon where solids, liquids, gases, and their mixtures erupt to the surface of an astronomical body. It is caused by the presence of an internal heat source in the body. Inside the body, heat partially melts solid material or turns material into gas. The mobilized material rises through the body's interior and then, if conditions are favorable, the mobile material breaks through the solid surface.
Enceladus is the sixth-largest moon of Saturn. It is about 500 kilometers in diameter, about a tenth of that of Saturn's largest moon, Titan. It is mostly covered by fresh, clean ice, making it one of the most reflective bodies of the Solar System. Consequently, its surface temperature at noon reaches only −198 °C, far colder than a light-absorbing body would be. Despite its small size, Enceladus has a wide variety of surface features, ranging from old, heavily cratered regions to young, tectonically deformed terrain.
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.
The tiger stripes of Enceladus consist of four sub-parallel, linear depressions in the south polar region of the Saturnian moon. First observed on May 20, 2005, by the Cassini spacecraft's Imaging Science Sub-system (ISS) camera, the features are most notable in lower resolution images by their brightness contrast from the surrounding terrain. Higher resolution observations were obtained by Cassini's various instruments during a close flyby of Enceladus on July 14, 2005. These observations revealed the tiger stripes to be low ridges with a central fracture. Observations from the Composite Infrared Spectrometer (CIRS) instrument showed the tiger stripes to have elevated surface temperatures, indicative of present-day cryovolcanism on Enceladus centered on the tiger stripes.
Ceres is a dwarf planet in the middle main asteroid belt between the orbits of Mars and Jupiter. It was the first known asteroid, discovered on 1 January 1801 by Giuseppe Piazzi at Palermo Astronomical Observatory in Sicily, and announced as a new planet. Ceres was later classified as an asteroid and then a dwarf planet, the only one always inside Neptune's orbit.
An ocean world, ocean planet or water world is a type of planet that contains a substantial amount of water in the form of oceans, as part of its hydrosphere, either beneath the surface, as subsurface oceans, or on the surface, potentially submerging all dry land. The term ocean world is also used sometimes for astronomical bodies with an ocean composed of a different fluid or thalassogen, such as lava, ammonia or hydrocarbons. The study of extraterrestrial oceans is referred to as planetary oceanography.
Extraterrestrial liquid water is water in its liquid state that naturally occurs outside Earth. It is a subject of wide interest because it is recognized as one of the key prerequisites for life as we know it and is thus surmised to be essential for extraterrestrial life.
The atmosphere of Triton is the layer of gases surrounding Triton. Like the atmospheres of Titan and Pluto, Triton's atmosphere is composed primarily of nitrogen, with a smaller component of methane. It hosts a layer of organic haze extending up to 30 kilometers above its surface and a deck of thin bright clouds at about 4 kilometers in altitude. Due to Triton's low gravity, its atmosphere is rather bloated, extending 800 kilometers from its surface.
In astronomy, a regular moon or a regular satellite is a natural satellite following a relatively close, stable, and circular orbit which is generally aligned to its primary's equator. They form within discs of debris and gas that once surrounded their primary, usually the aftermath of a large collision or leftover material accumulated from the protoplanetary disc. Young regular moons then begin to accumulate material within the circumplanetary disc in a process similar to planetary accretion, as opposed to irregular moons, which formed independently before being captured into orbit around the primary.
A planetary surface is where the solid or liquid material of certain types of astronomical objects contacts the atmosphere or outer space. Planetary surfaces are found on solid objects of planetary mass, including terrestrial planets, dwarf planets, natural satellites, planetesimals and many other small Solar System bodies (SSSBs). The study of planetary surfaces is a field of planetary geology known as surface geology, but also a focus on a number of fields including planetary cartography, topography, geomorphology, atmospheric sciences, and astronomy. Land is the term given to non-liquid planetary surfaces. The term landing is used to describe the collision of an object with a planetary surface and is usually at a velocity in which the object can remain intact and remain attached.
Planetary oceanography, also called astro-oceanography or exo-oceanography, is the study of oceans on planets and moons other than Earth. Unlike other planetary sciences like astrobiology, astrochemistry, and planetary geology, it only began after the discovery of underground oceans in Saturn's moon Titan and Jupiter's moon Europa. This field remains speculative until further missions reach the oceans beneath the rock or ice layer of the moons. There are many theories about oceans or even ocean worlds of celestial bodies in the Solar System, from oceans made of diamond in Neptune to a gigantic ocean of liquid hydrogen that may exist underneath Jupiter's surface.
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.
Kerwan is the largest confirmed crater and one of the largest geological features on Ceres. It was discovered on February 19, 2015 from Dawn images as it approached Ceres. The crater is distinctly shallow for its size, and lacks a central peak. A central peak might have been destroyed by a 15-kilometer-wide crater at the center of Kerwan. The crater is likely to be young relative to the rest of Ceres's surface, as Kerwan has largely obliterated the cratering in the southern part of Vendimia Planitia.
Wright Mons is a large, roughly circular mountain and likely cryovolcano on the dwarf planet Pluto. It is located southwest of Sputnik Planitia near the center of the low-lying Hyecho Palus region, adjacent to the Tenzing Montes and Belton Regio. A relatively young geological feature, Wright Mons has attracted attention as one of the most apparent examples of recent geological activity on Pluto.
Lynnae C. Quick is an American planetary geophysicist and Ocean Worlds Planetary Scientist at NASA Goddard Space Flight Center. Her research centers on theoretical modeling of cryovolcanic processes on the icy moons and dwarf planets in the Solar System as well as modeling volcanic activity on Venus and the Moon. Quick is a member of the Dawn, Europa Clipper, and Dragonfly Mission science teams. She is also a member of the NASA Solar System Exploration Research Virtual Institute (SSERVI) Toolbox for Research and Exploration (TREX) team, and serves as co-chair of the Earth and Planetary Systems Sciences section of the National Society of Black Physicists.
The geology of Triton encompasses the physical characteristics of the surface, internal structure, and geological history of Neptune's largest moon Triton. With a mean density of 2.061 g/cm3, Triton is roughly 15-35% water ice by mass; Triton is a differentiated body, with an icy solid crust atop a probable subsurface ocean and a rocky core. As a result, Triton's surface geology is largely driven by the dynamics of water ice and other volatiles such as nitrogen and methane. Triton's geology is vigorous, and has been and continues to be influenced by its unusual history of capture, high internal heat, and its thin but significant atmosphere.