Mercury is the smallest planet in the Solar System and the closest to the Sun. Its orbit around the Sun takes 87.97 Earth days, the shortest of all the Sun's planets. It is named after the Roman god Mercurius (Mercury), god of commerce, messenger of the gods, and mediator between gods and mortals, corresponding to the Greek god Hermes. Like Venus, Mercury orbits the Sun within Earth's orbit as an inferior planet; its apparent distance from the Sun as viewed from Earth never exceeds 28°. This proximity to the Sun means the planet can only be seen near the western horizon after sunset or the eastern horizon before sunrise, usually in twilight. At this time, it may appear as a bright star-like object, but is more difficult to observe than Venus. From Earth, the planet telescopically displays the complete range of phases, similar to Venus and the Moon, which recurs over its synodic period of approximately 116 days. Due to its synodic proximity to Earth, Mercury is most often the closest planet to Earth, with Venus periodically taking this role.
The geology of Mercury is the scientific study of the surface, crust, and interior of the planet Mercury. 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.
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.
Lermontov is an impact crater on the planet Mercury. The crater is named after Mikhail Yuryevich Lermontov, a 19th-century Russian poet. The name was approved by the International Astronomical Union in 1976.
The Borealis quadrangle is a quadrangle on Mercury surrounding the north pole down to 65° latitude. It was mapped in its entirety by the MESSENGER spacecraft, which orbited the planet from 2008 to 2015, excluding areas of permanent shadow near the north pole. Only approximately 25% of the quadrangle was imaged by the Mariner 10 spacecraft during its flybys in 1974 and 1975. The quadrangle is now called H-1.
The Shakespeare quadrangle is a region of Mercury running from 90 to 180° longitude and 20 to 70° latitude. It is also called Caduceata.
The Bach quadrangle encompasses the south polar part of Mercury poleward of latitude 65° S. It is named after the prominent crater Bach within the quadrangle, which is in turn named after Baroque composer Johann Sebastian Bach. The quadrangle is now called H-15.
Apollodorus is an impact crater on Mercury. Its unusual appearance, with radiating dark troughs, led to a nickname of "the Spider" by scientists before its official name was decided. Apollodorus is located near the center of Pantheon Fossae, which is a system of radial grabens situated in the inner part of the Caloris basin. The floor, rim and walls of Apollodorus expose a low reflectance material (LRM) excavated during the impact from beneath the light volcanic plains, which cover the central part of the Caloris.
Praxiteles is a crater on Mercury. It is one of 110 peak ring basins on Mercury.
Raditladi is a large impact crater on Mercury with a diameter of 263 km. Inside its peak ring there is a system of concentric extensional troughs (graben), which are rare surface features on Mercury. The floor of Raditladi is partially covered by relatively light smooth plains, which are thought to be a product of the effusive volcanism. The troughs may also have resulted from volcanic processes under the floor of Raditladi. The basin is relatively young, probably younger than one billion years, with only a few small impact craters on its floor and with well-preserved basin walls and peak-ring structure. It is one of 110 peak ring basins on Mercury.
Beckett is a pit-floored crater on Mercury, which was discovered in January 2008 during the first flyby of the planet by the MESSENGER spacecraft. The crater was named in November 2008 by the IAU.
Glinka is a pit-floored crater on Mercury, which was discovered in 1974 by Mariner 10 spacecraft. It was named by the IAU in 2008, after Russian composer Mikhail Glinka.
Scarlatti is a pit-floored crater on Mercury, which was discovered in 1974 by the Mariner 10 spacecraft. It has a prominent peak ring, and it is one of 110 peak ring basins on Mercury. The crater floor is covered by the smooth plains material. The crater displays an arcuate collapse feature along the northeastern peak ring. The size of the pit, which was first noticed in MESSENGER images obtained in January 2008, is 38 × 12 km. Such a feature may have resulted from collapse of a magma chamber underlying the central peak ring complex of the crater. The collapse feature is an analog of Earth's volcanic calderas. Scarlatti is thought to have the same age as the Caloris basin.
To Ngoc Van is a pit-floored crater on Mercury, named after the Vietnamese artist Tô Ngọc Vân. It was discovered in January 2008 during the first flyby of the planet by MESSENGER spacecraft. Its floor displays an irregularly shaped collapse feature, which is called a central pit. The size of the pit is 21 × 10 km. Such a feature may have resulted from collapse of a magma chamber underlying the central part of the crater. The collapse feature is an analog of Earth's volcanic calderas.
Picasso is a crater on Mercury. It has drawn scientific attention because of the large, arc-shaped pit crater located on the eastern side of its floor. Similar pits have been discovered on the floors of several other Mercury craters, such as Beckett and Gibran. These pits are postulated to have formed when subsurface magma subsided or drained, causing the surface to collapse into the resulting void. If this interpretation is correct, pit-floor craters such as Picasso provide evidence of shallow magmatic activity in Mercury's history.
Mars may contain ores that would be very useful to potential colonists. The abundance of volcanic features together with widespread cratering are strong evidence for a variety of ores. While nothing may be found on Mars that would justify the high cost of transport to Earth, the more ores that future colonists can obtain from Mars, the easier it would be to build colonies there.
Ghost craters on the planet Mercury have tectonic features such as graben and wrinkle ridges. These features were formed by extensional and contractional forces originating in tectonic processes such as uplift and global contraction. The combination of graben and wrinkle ridges inside ghost craters found on Mercury has not been observed on any of the other terrestrial planets.
Inter-crater plains on Mercury are a land-form consisting of plains between craters on Mercury.
A crater is a landform consisting of a hole or depression on a planetary surface, usually caused either by an object hitting the surface, or by geological activity on the planet. A crater has classically been described as: "a bowl-shaped pit that is formed by a volcano, an explosion, or a meteorite impact". On Earth, craters are "generally the result of volcanic eruptions", while "meteorite impact craters are common on the Moon, but are rare on Earth".
Pahinui is a crater on Mercury. Its name was adopted by the International Astronomical Union in 2016, after the Hawaiian musician, Charles Phillip Kahahawai "Gabby" Pahinui.
