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 in 1976 by the IAU. It was first observed in detail by Mariner 10. The plain is approximately 473 kilometers in diameter.
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.
The Michelangelo quadrangle is in the southern hemisphere of the planet Mercury, where the imaged part is heavily cratered terrain that has been strongly influenced by the presence of multiring basins. At least four such basins, now nearly obliterated, have largely controlled the distribution of plains materials and structural trends in the map area. Many craters, interpreted to be of impact origin, display a spectrum of modification styles and degradation states. The interaction between basins, craters, and plains in this quadrangle provides important clues to geologic processes that have formed the morphology of the mercurian surface.
Mozart is a crater on Mercury, named by the IAU in 1976 after Austrian composer Wolfgang Amadeus Mozart.
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.
Hovnatanian is a crater on Mercury. Its “butterfly” pattern of ejecta rays were created by an impact at an even lower angle than that which formed neighboring Qi Baishi crater. From the "butterfly" pattern of rays, the Hovnatanian impactor was travelling either north-to-south or south-to-north prior to hitting Mercury's surface. Hovnatanian lies to the west of Tir 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 a 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.
Amru Al-Qays is a crater on Mercury. The crater was first imaged by Mariner 10 in 1974. Its name was adopted by the IAU in 1976, after the pre-Islamic Arab poet Imru' al-Qais in honor of his impact on astronomy and the world.
Kālidāsā is a crater on Mercury. Its name was adopted by the International Astronomical Union in 1976. Kalidasa is named for the Indian writer Kālidāsa, who lived in the 5th century CE.
Inter-crater plains on Mercury are a land-form consisting of plains between craters on Mercury.
Mearcair Planitia is a large plain on the planet Mercury. The name Mearcair is the Irish 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.
Stilbon Planitia is a large plain on the planet Mercury. The name Stilbon is ancient Greek word for "Mercury", and the name was approved in 2017. It was first observed in detail by MESSENGER. It lies north of the Caloris basin, and is approximately 1550 kilometers long.
Exaggerated color image of part of Tir Planitia by MESSENGER. Hovnatanian crater is in lower left.
Oblique view of Fet crater (upper left) in Tir Planitia, showing the nature of the smooth plain.
