Hollows are a landform on the planet Mercury, discovered during the MESSENGER mission that orbited the planet from 2011 to 2015.
Hollows are typically clusters of rimless depressions with flat floors and haloes of bright (high albedo) material surrounding them. Hollows are thought to form by loss of volatiles from the surface by sublimation, caused by the intense solar radiation on the airless planet. They are some of the youngest features on Mercury. [1]
Hollows were first observed as bright areas within craters imaged by the Mariner 10 spacecraft in 1974, but the images were not of sufficient resolution to discern any detail. These craters include Balzac, Tyagaraja, Theophanes, Zeami, and Hopper. [2]
The MESSENGER spacecraft imaged the rest of the planet, much of it at higher resolution and in color, leading to the discovery of hollows and clues about their formation and nature. Other craters where hollows are present include Warhol, Xiao Zhao, Seuss, Wergeland, Raditladi, Sholem Aleichem, Lermontov, Darío, and Scarlatti. Kertész, Sander, Sontag, Nāwahī, and Balanchine are craters with hollows within the Caloris basin. There are many other examples, and some hollows occur on the plains between craters (see Canova crater).
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.
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 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 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.
Sholem Aleichem is a crater on Mercury, named after the Yiddish writer Sholem Aleichem. The inter-crater plain deposits have been deformed by linear ridges.
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.
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.
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.
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.
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.
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.
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.
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.
Al-Hamadhani is a crater on Mercury. It has a diameter of 186 kilometers. Its name was adopted by the International Astronomical Union in 1979. Al-Hamadhani is named for the Iranian writer Badi' al-Zaman al-Hamadani, who died in 1007 C.E.
Bartók is a crater on Mercury. Its name was adopted by the International Astronomical Union (IAU) in 1979. Bartók is named for the Hungarian composer Béla Bartók, who lived from 1881 to 1945.
Han Kan is a crater on Mercury. It has a diameter of 50 kilometers. Its name was adopted by the International Astronomical Union (IAU) in 1985. Han Kan is named for the Chinese painter Han Gan, who lived from 720 to 780.
Tyagaraja is a crater on Mercury. Its name was adopted by the International Astronomical Union in 1976. Tyagaraja is named for the Indian composer Tyagaraja.
Hopper is a crater on Mercury. Its name was adopted by the IAU in 2012, after the American painter Edward Hopper.