An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.
Located on Jupiter's moon Callisto, Valhalla is the largest multi-ring impact crater in the Solar System. It is named after Valhalla, the hall where warriors are taken after death in Norse mythology.
Cleopatra, initially called Cleopatra Patera, is an impact crater on Venus, in Maxwell Montes.
The geology of solar terrestrial planets mainly deals with the geological aspects of the four terrestrial planets of the Solar System – Mercury, Venus, Earth, and Mars – and one terrestrial dwarf planet: Ceres. Earth is the only terrestrial planet known to have an active hydrosphere.
The Borealis quadrangle is a quadrangle on Mercury surrounding the north pole down to 65° latitude.
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 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.
The Bach quadrangle encompasses the south polar part of Mercury poleward of latitude 65° S. It is named after the prominent crater Bach (crater) within the quadrangle, which is in turn named after Baroque composer Johann Sebastian Bach. The quadrangle is now called H-15.
The Beethoven quadrangle is located in the equatorial region of Mercury, in the center of the area imaged by Mariner 10. Most pictures of the quadrangle were obtained at high sun angles as the Mariner 10 spacecraft receded from the planet. Geologic map units are described and classified on the basis of morphology, texture, and albedo, and they are assigned relative ages based on stratigraphic relations and on visual comparisons of the density of superposed craters. Crater ages are established by relative freshness of appearance, as indicated by topographic sharpness of their rim crests and degree of preservation of interior and exterior features such as crater floors, walls, and ejecta aprons. Generally, topography appears highly subdued because of the sun angle, and boundaries between map units are not clearly defined.
The Discovery quadrangle lies within the heavily cratered part of Mercury in a region roughly antipodal to the 1550-km-wide Caloris Basin. Like the rest of the heavily cratered part of the planet, the quadrangle contains a spectrum of craters and basins ranging in size from those at the limit of resolution of the best photographs to those as much as 350 km across, and ranging in degree of freshness from pristine to severely degraded. Interspersed with the craters and basins both in space and time are plains deposits that are probably of several different origins. Because of its small size and very early segregation into core and crust, Mercury has seemingly been a dead planet for a long time—possibly longer than the Moon. Its geologic history, therefore, records with considerable clarity some of the earliest and most violent events that took place in the inner Solar System.
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.
Dickinson crater is located at 74.6 degrees north latitude and 177.2 east longitude, in the northeastern Atalanta Region of Venus. It is 69 kilometers (43 mi) in diameter. The crater is complex, characterized by a partial central ring and a floor flooded by radar-dark and radar-bright materials. Hummocky, rough-textured ejecta extend all around the crater, except to the west. The lack of ejecta to the west may indicate that the impactor that produced the crater was an oblique impact from the west. Extensive radar-bright flows that emanate from the crater's eastern walls may represent large volumes of impact melt, or they may be the result of volcanic material released from the subsurface during the cratering event.
Lofn is a large relatively young impact crater on Jupiter's Galilean satellite Callisto. It was identified in 1997 and named after the goddess of marriage in Norse mythology. Located near the south pole of this moon, Lofn is classified as a flat floored or anomalous dome impact crater. It is superimposed on Adlinda multilayer structure obscuring about 30% of it. Another multi-ring structure—Heimdall is found to the south-west of Lofn.
Rembrandt is a large impact crater on Mercury. With a diameter of 715 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.
Raditladi Basin is a large peak ring 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.
Complex craters are a type of large impact crater morphology.
Denning Crater is a large Noachian-age impact crater in the southwestern Terra Sabaea region of the southern Martian highlands, within the Sinus Sabaeus quadrangle. It is located to the northwest of the Hellas impact basin within the furthest outskirts of the Hellas debris apron. The crater is 165 km in diameter and likely formed during the Late Heavy Bombardment, a period of intense bolide impacts affecting the entirety of the Solar System; during the Hesperian period, aeolian processes caused significant degradation of the crater's rim features and infilled the crater's floor. Similar to other large craters in this region of Mars, wind-eroded features are sporadically found on the basin floor. The presence of wrinkle ridges of varying orientations within and around the Denning basin has been correlated to regional tectonic events, including the formation of the Hellas basin itself. The crater was named for British astronomer William Frederick Denning.
