In planetary geology, a ray system comprises radial streaks of fine ejecta thrown out during the formation of an impact crater, looking somewhat like many thin spokes coming from the hub of a wheel. The rays may extend for lengths up to several times the diameter of their originating crater, and are often accompanied by small secondary craters formed by larger chunks of ejecta. Ray systems have been identified on the Moon, Earth, Mercury, and some moons of the outer planets. Originally it was thought that they existed only on planets or moons lacking an atmosphere, but more recently they have been identified on Mars in infrared images taken from orbit by 2001 Mars Odyssey's thermal imager.
Degas is a rayed crater on Mercury at latitude 37.5 N, longitude 127 W. Its diameter is 54 kilometres (34 mi). It was named after the French impressionist painter Edgar Degas in 1979. The rays consist of light colored material blasted out during the crater's formation. Craters older than Degas are covered by the ray material, while younger craters are seen superimposed on the rays. Degas forms a crater pair with Brontë to the north. Both lie near the center of Sobkou Planitia.
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.
Odinigwe Benedict Chukwukadibia Enwonwu MBE, better known as Ben Enwonwu, was a Nigerian painter and sculptor. Arguably the most influential African artist of the 20th century, his pioneering career opened the way for the postcolonial proliferation and increased visibility of modern African art. He was one of the first African artists to win critical acclaim, having exhibited in august exhibition spaces in Europe and the United States and listed in international directories of contemporary art. Since 1950, Enwonwu was celebrated as "Africa's Greatest Artist" by the international media and his fame was used to enlist support for Black Nationalists movement all over the world. The Enwonwu crater on the planet Mercury is named in his honour.
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.
Kuiper is a moderate-size crater with a central peak cluster located at 11.35°S 31.23°W on Mercury. It is 62 kilometers in diameter and was named after Dutch-American astronomer Gerard Kuiper in 1976. It is one of only 2 Mercurian craters which are named not after artists, and one of very few cases when the same name is used for 3 craters. Gerard Kuiper, being a leader of American planetary science, died shortly before the first images of Mercurian surface were made.
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 Kuiper quadrangle, located in a heavily cratered region of Mercury, includes the young, 55-km-diameter crater Kuiper, which has the highest albedo recorded on the planet, and the small crater Hun Kal, which is the principal reference point for Mercurian longitude. Impact craters and basins, their numerous secondary craters, and heavily to lightly cratered plains are the characteristic landforms of the region. At least six multiringed basins ranging from 150 km to 440 km in diameter are present. Inasmuch as multiringed basins occur widely on that part of Mercury photographed by Mariner 10, as well as on the Moon and Mars, they offer a potentially valuable basis for comparison between these planetary bodies.
Bashō is a crater on Mercury named after Matsuo Bashō, a 17th-century Japanese writer. Bashō crater is only 74.62 kilometers (46.37 mi) in diameter, but is a prominent feature on Mercury's surface, due to its bright rays. Photographs from NASA's Mariner 10 and MESSENGER spacecraft show a curious halo of dark material around the crater.
Xiao Zhao crater is small in comparison with many other craters on Mercury. However, Xiao Zhao's long bright rays make it a readily visible feature. The fresh, bright rays, which were created by material ejected outward during the impact event that formed the crater, indicate that Xiao Zhao is a relatively young crater on Mercury's surface.
Sander is a crater on Mercury within Caloris Basin. It has dark walls and bright patches on its floor. Unlike the rays of Bashō crater, the bright areas are not believed to be immature, but they are inherently bright. It is named after the German photographer August Sander (1876–1964).
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.
Amaral is a crater on the planet Mercury. With its smooth floor, surrounding ejecta, and small secondary craters, it appears noticeably younger than the heavily cratered surface around it. Along with a smooth crater floor, Amaral also has a central peak. Bright material on this peak is of particular interest as it appears to have an unusual color. In color-enhanced images, the central peak of Amaral appears as a bright blue color in striking contrast to the otherwise orange tones of surface material nearby. The different color of the central peak likely indicates rocks with different chemical composition from those on the neighboring surface.
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.
Berkel is a crater on the planet Mercury. Its name was approved by the IAU on July 9, 2009. It was named after the modernist painter Sabri Berkel.
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.
Copland is an impact crater on Mercury. Its floor is flooded with volcanic smooth plains material, which could be related to the activity that formed the nearby bright vent known as Nathair Facula.
Dominici is a crater on Mercury. Dominici's bright rays indicate that it is relatively young, and the young rays appear light blue in enhanced-color images. Dominici also has bright material on its floor and is surrounded by crater ejecta and material that appears orange in enhanced color. These color differences, as in nearby Titian crater, suggest that the impact crater excavated material from beneath Mercury's surface that differs in composition from the surrounding surface. Dominici lies within a much larger impact structure, the Homer basin.
Carolan is a crater on Mercury. Its name was suggested by an Irishman, Fergal Donnelly, and two Americans, Joseph Brusseau and Deane Morrison, in a naming contest which was eventually adopted by the International Astronomical Union (IAU) on 2015. Carolan is named for the Irish composer and performer Turlough O'Carolan, who lived from 1670 to 1738 C.E. The craters Kulthum, Enheduanna, Karsh, and Rivera were also named as part of the contest.
MESSENGER NAC image
Oblique view with north at left
Enwonwu crater rays
