Caloris Planitia is a plain within a large impact basin on Mercury, informally named Caloris, about 1,550 km (960 mi) in diameter. It is one of the largest impact basins in the Solar System. "Calor" is Latin for "heat" and the basin is so-named because the Sun is almost directly overhead every second time Mercury passes perihelion. The crater, discovered in 1974, is surrounded by the Caloris Montes, a ring of mountains approximately 2 km (1.2 mi) tall.
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.
Odin Planitia is a large basin on Mercury. It was named after the Norse god Odin, who was sometimes considered to be the equivalent of the Roman god Mercury, in 1976 by the IAU. It was first observed in detail by Mariner 10. The plain is approximately 473 kilometers in diameter.
Suisei Planitia is a large area of smooth plains on Mercury, approximately 570 km wide. Ghost craters are unusual forms that occur in the Suisei Planitia. They are buried and rounded in profile, with only their rim crests rising above the surrounding smooth plains. It has been suggested that material forming Suisei Planitia is ejecta from the impact that formed Caloris Planitia. The name for this Planitia was approved in 1976 by the IAU.
Tir Planitia is a large plain on the planet Mercury. The name Tir (تیر) is the Persian word for "Mercury", and the name was approved in 1976. It was first observed in detail by Mariner 10. It lies between the large crater Mozart and the ancient Tolstoj basin.
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.
Goethe Basin is an impact basin at 81.4° N, 54.3° W on Mercury approximately 317 kilometers in diameter. It is named after German poet Johann Wolfgang von Goethe.
The Tolstoj quadrangle in the equatorial region of Mercury runs from 144 to 216° longitude and -25 to 25° latitude. It was provisionally called "Tir", but renamed after Leo Tolstoy by the International Astronomical Union in 1976. Also called Phaethontias.
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 Caloris group is a set of geologic units on Mercury. McCauley and others have proposed the name “Caloris Group” to include the mappable units created by the impact that formed the Caloris Basin and have formally named four formations within the group, which were first recognized and named informally by Trask and Guest based on imagery from the Mariner 10 spacecraft that flew by Mercury in 1974 and 1975. The extent of the formations within the group have been expanded and refined based on imagery and other data from the MESSENGER spacecraft which orbited Mercury from 2011 to 2015, and imaged parts of the planet that were in shadow at the time of the Mariner 10 encounters.
The Eminescu quadrangle (H-9) is one of fifteen quadrangles on Mercury. It runs from 216 to 288° longitude and from -25 to 25° latitude. Named after the Eminescu crater, it was mapped in detail for the first time after MESSENGER entered orbit around Mercury in 2011. It had not been mapped prior to that point because it was one of the six quadrangles that was not illuminated when Mariner 10 made its flybys in 1974 and 1975. These six quadrangles continued to be known by their albedo feature names, with this one known as the Solitudo Criophori quadrangle.
Mozart is a crater on Mercury, named by the IAU in 1976 after Austrian composer Wolfgang Amadeus Mozart.
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.
Rembrandt is a large impact crater on Mercury. With a diameter of 716 km it is the second-largest impact basin on the planet, after Caloris, and is one of the larger craters in the Solar System. It was discovered by MESSENGER during its second flyby of Mercury on October 6, 2008. The crater is 3.9 billion years old, and was created during the period of Late Heavy Bombardment. The density and size distribution of impact craters along Rembrandt's rim indicate that it is one of the youngest impact basins on Mercury.
The crater Oskison is located in the far northern hemisphere of Mercury, in the plains north of Caloris basin. Oskison is a distinctive crater with a large central peak that exposes material excavated from depth. Many chains of secondary craters are visible radiating from Oskison outward onto the surrounding smooth plains, known as Stilbon Planitia.
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.
Rachmaninoff is an impact crater on Mercury. This basin, first imaged in its entirety during MESSENGER's third Mercury flyby, was quickly identified as a feature of high scientific interest, because of its fresh appearance, its distinctively colored interior plains, and the extensional troughs on its floor. The morphology of Rachmaninoff is similar to that of Raditladi, which is one of the youngest impact basins on Mercury. The age of Raditladi is estimated at one billion years. Rachmaninoff appears to be only slightly older.
Inter-crater plains on Mercury are a land-form consisting of plains between craters on Mercury.
Holst is a crater on Mercury. Its name was adopted by the International Astronomical Union (IAU) on April 24, 2012.
Mearcair Planitia is a large plain on the planet Mercury. The name Mearcair is the Irish and Scottish Gaelic word for "Mercury", and the name was approved in 2017. It was first observed in detail by MESSENGER. It lies between the large crater Raditladi and the ancient Caloris basin.
