MESSENGER was a NASA robotic space probe that orbited the planet Mercury between 2011 and 2015, studying Mercury's chemical composition, geology, and magnetic field. The name is a backronym for "Mercury Surface, Space Environment, Geochemistry, and Ranging", and a reference to the messenger god Mercury from Roman mythology.
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.
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.
Tolstoj is a large, ancient impact crater on Mercury. It was named after Leo Tolstoy by the IAU in 1976. The albedo feature Solitudo Maiae appears to be associated with this crater.
The Hokusai quadrangle (H-5) is one of fifteen quadrangles on the planet Mercury. It runs from 360 to 270° longitude and 20 to 70° latitude. Named after the Hokusai 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 Apollonia quadrangle.
Eminescu is a peak ring crater on Mercury 125 kilometers (78 mi) in diameter. Since there are very few later craters superposed on it, Eminescu appears to be a young crater formed around one billion years ago. It has a transitional morphology between larger more complex impact basins like Raditladi and smaller simpler central peak craters.
Verdi is an impact crater on the planet Mercury. It was named after Italian Romantic composer Giuseppe Verdi (1813–1901) in 1979, as recognized by the International Astronomical Union. The crater's extensive ejecta blanket and secondary crater field are superposed on plains materials and older craters.
Polygnotus is a crater on Mercury, named by the IAU in 1976, after ancient Greek painter Polygnotus.
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.
Navoi is a crater on Mercury. It contains uncommon reddish material that indicates a different rock composition from its surroundings. Navoi also appears to have an irregularly shaped depression in its center. Such depressions have been seen elsewhere on Mercury, including within Praxiteles crater, and may indicate past volcanic activity.
Enwonwu is an impact crater on the planet Mercury. It is named in honor of Ben Enwonwu, the modernist Nigerian sculptor and painter. The crater displays a central peak and a set of bright rays emanating from the crater rim. The rays cross the surrounding surface and neighboring craters, indicating that Enwonwu crater was formed comparatively recently in Mercury's history. The brightness of the rays also suggests relative youth, as over time rays darken and disappear on Mercury's surface.
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.
Hokusai is a rayed impact crater on Mercury, which was discovered in 1991 by ground-based radar observations conducted at Goldstone Observatory. The crater was initially known as feature B. Its appearance was so dissimilar to other impact craters that it was once thought to be a shield volcano. However, improved radar images by the Arecibo Observatory obtained later in 2000–2005 clearly showed that feature B is an impact crater with an extensive ray system. The bright appearance of rays in the radio images indicates that the crater is geologically young; fresh impact ejecta has a rough surface, which leads to strong scattering of radio waves.
Debussy is a rayed impact crater on Mercury, which was discovered in 1969 by low resolution ground-based radar observations obtained by the Goldstone Observatory. Later in 1990–2005 it was imaged in more detail by the Arecibo Observatory. The crater was initially known as the feature A. The bright appearance of rays in the radar images indicates that the crater is geologically young, because fresh and rough surfaces of young impact craters are good scatterers of radio waves.
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.
Renoir is a crater on the planet Mercury. Its name, after the French painter Pierre-Auguste Renoir (1841–1919), was adopted by the International Astronomical Union in 1976.
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.
Holst is a crater on Mercury. Its name was adopted by the International Astronomical Union (IAU) on April 24, 2012.
Faulkner is a crater on Mercury. It has a diameter of 168 kilometres. Its name was adopted by the International Astronomical Union (IAU) on April 24, 2012. Faulkner is named for the American author William Faulkner.
Oskison crater
Smaller crater on the west rim of Oskison
Exaggerated color view of Oskison crater, looking northwest
