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This article is about impact craters, also known as meteor craters. For the specific crater named Meteor Crater, see Barringer Crater. For other types of craters, see Crater. The Barringer Crater, also known as the Meteor Crater, is a famous impact crater created by a meteorite, located about 55 kilometers east of Flagstaff in the northern Arizona desert (USA). ...
The word crater may refer to A landform resembling a pit or depression in the topography that can be formed in several ways: speculation exists that a meteorite impact with another body can cause an impact crater, an electrical discharge on any scale tends to form circular craters, volcanic activity...
An impact crater (impact basin or sometimes crater) is a circular depression on a surface, usually referring to a planet, moon, asteroid, or other celestial body, caused by a collision of a smaller body (meteorite) with the surface. In the center of craters on Earth a crater lake often accumulates, and a central island or peak (caused by rebounding crustal rock after the impact) is usually a prominent feature in the lake. Description: The prominent Tycho crater on the Moon. ...
Description: The prominent Tycho crater on the Moon. ...
Tycho is a prominent lunar impact crater located in the southern lunar highlands. ...
Earth, also known as the Earth or Terra, is the third planet outward from the Sun. ...
Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ...
A planet in common parlance is a large object in orbit around a star that is not a star itself. ...
Moons of solar system scaled to Earths Moon The common noun moon (not capitalized) is used to mean any natural satellite of the other planets. ...
An asteroid is a small, solid object in our Solar System, orbiting the Sun. ...
Bacubirito in Culiacan, Mexico is the second largest meteorite in the Americas, and fifth largest in the world A meteorite is a small extraterrestrial body that reaches the Earths surface. ...
Earth, also known as the Earth, Terra, and (mostly in the 19th century) Tellus, is the third planet outward from the Sun. ...
For the general term of a geological feature that goes by the same name, see crater lake. ...
Ancient craters whose relief has disappeared leaving only a "ghost" of a crater are known as palimpsests. Although it might be assumed that a major impact on the Earth would leave behind absolutely unmistakable evidence, in fact the gradual processes that change the surface of the Earth tend to cover the effects of impacts. Erosion by wind and water, deposits of wind-blown sand and water-carried sediment, and lava flows in due time tend to obscure or bury the craters left by impacts. Simple slumping of weak crustal material can also play a role, especially on outer solar system bodies such as Callisto which are covered in a crust of ice. A palimpsest is a manuscript page, scroll, or book that has been written on, scraped off, and used again. ...
Look up Erosion in Wiktionary, the free dictionary Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case...
Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of water or other liquid. ...
Atmospheric characteristics Atmospheric pressure trace Carbon dioxide 100% Callisto (ka-lis-toe, Greek Καλλιστώ) is a moon of the planet Jupiter, discovered in 1610 by Galileo Galilei. ...
However, some evidence remains, and over 150 major craters have been identified on the Earth. Studies of these craters have allowed geologists to find the remaining traces of other craters that have mostly been obliterated. Impact craters are found on nearly all solid surface planets and satellites. As the number of impact craters increases on a surface, the appearance of the surfaces changes; this can be used to establish the age of extraterrestrial terrain. After a period of time, however, an equilibrium is reached in which old craters are destroyed as quickly as new craters form. Geology (from Greek γη- (ge-, the earth) and λογος (logos, word, reason)) is the science and study of the Earth, its composition, structure, physical properties, history, and the processes that shape it. ...
History Daniel Barringer (1860-1929) was one of the first to identify a geological structure as an impact crater, the Barringer Meteorite Crater (or the "Meteor Crater") in Arizona, but at the time his ideas were not widely accepted, and when they were, there was no recognition of the fact that Earth impacts are common in geological terms. Download high resolution version (1600x320, 152 KB)This is an image that I took of Meteor Crater in Arizona. ...
Download high resolution version (1600x320, 152 KB)This is an image that I took of Meteor Crater in Arizona. ...
Daniel M. Barringer Daniel Moreau Barringer (1860 – 1929) is best known for being the first person to prove the existence of a meteorite crater on Earth, the Barringer Meteorite Crater, or Meteor Crater, in Arizona. ...
Bacubirito in Culiacan, Mexico is the second largest meteorite in the Americas, and fifth largest in the world A meteorite is a small extraterrestrial body that reaches the Earths surface. ...
The Barringer Crater, also known as the Meteor Crater, is a famous impact crater created by a meteorite, located about 55 kilometers east of Flagstaff in the northern Arizona desert (USA). ...
State nickname: The Grand Canyon State, The Copper State Other U.S. States Capital Phoenix Largest city Phoenix Governor Janet Napolitano (D) Official languages English Only State Area 295,254 km² (6th) - Land 294,312 km² - Water 942 km² (0. ...
In the 1920s, the American geologist Walter H. Bucher studied a number of craters in the US. He concluded they had been created by some great explosive event, but believed they were the result of some massive volcanic eruption. However, in 1936, the geologists John D. Boon and Claude C. Albritton Jr. revisited Bucher's studies and concluded the craters he studied were probably formed by impacts.
The issue remained more or less speculative until the 1960s. A number of researchers, most notably Eugene M. Shoemaker, conducted detailed studies of the craters that provided clear evidence that they had been created by impacts, identifying the shock-metamorphic effects uniquely associated with impacts, of which the most familiar is Shocked quartz. Eugene Shoemaker at a stereoscopic microscope used for asteroid discovery Eugene Merle Shoemaker (or Gene Shoemaker) (April 28, 1928 – July 18, 1997) was one of the founders of the fields of planetary science and is best known for co-discovering the Comet Shoemaker-Levy 9 with his wife Carolyn Shoemaker...
Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. ...
Armed with the knowledge of shock-metamorphic features, Carlyle S. Beals and colleagues at the Dominion Observatory, (Victoria, British Columbia, Canada), and Wolf von Engelhardt of the University of Tübingen in Germany began a methodical search for "impact structures". By 1970, they had tentatively identified more than 50. The Dominion Observatory building The Dominion Observatory was an astronomical observatory in Ottawa, Canada that operated from 1905 to 1970. ...
The arms of Victoria. ...
Eberhard Karls University of Tübingen (German: Eberhard-Karls-Universität Tübingen) is a state-supported university located on the Neckar river, in the city of Tübingen, Baden-Württemberg, Germany. ...
Their work remained controversial, but the American Apollo Moon landings, which were in progress at the time, provided evidence of the rate of impact cratering on the Moon. Processes of erosion on the Moon are minimal and so craters persist almost indefinitely. Since the Earth could be expected to have roughly the same cratering rate as the Moon, it became clear that the Earth had suffered far more impacts than could be seen by counting evident craters. Description Role: Earth and Lunar Orbit Crew: 3; CDR, CM pilot, LM pilot Dimensions Height: 36. ...
Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ...
The age of known impact craters on the Earth ranges from about a thousand (e.g. the Haviland crater in Kansas) to almost two billion years, though few older than 200 million years have been found, as geological processes tend to obliterate older ones. They are also selectively found in the stable interior regions of continents. Few underwater craters have been discovered because of the difficulty of surveying the sea floor; the rapid rate of change of the ocean bottom; and the subduction of the ocean floor into the Earth's interior by processes of plate tectonics. File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
File history Legend: (cur) = this is the current file, (del) = delete this old version, (rev) = revert to this old version. ...
The Haviland Crater, also called the Brenham Crater, is a meteor crater in Kiowa County, Kansas. ...
A craton is an old and stable part of the continental crust that has survived the merging and splitting of continents and supercontinents for at least 500 million years. ...
Categories: Geology stubs | Plate tectonics ...
Plate tectonics (from the Greek word for one who constructs, τεκτων, tekton) is a theory of geology developed to explain the phenomenon of continental drift, and is currently the theory accepted by the vast majority of scientists working in this area. ...
Current estimates of the rate of cratering on the Earth suggest that from one to three craters with a width greater than 20 kilometers are created every million years. This indicates that there are far more relatively young craters on the planet than have been discovered so far.
Formation and structure An object falling from open space hits the Earth with a minimum velocity of 11.6 km/s (7 mi/s). Since the energy from motion grows as the square of the velocity, this gives moving rock more energy per kilogram than ordinary chemical explosives. Massive objects can easily cause kiloton explosions that resemble nuclear explosions. Seismographs record about one multikiloton impact somewhere on the Earth each year, usually in mid-ocean.
If the object weighs more than 1,000 tonnes, an atmosphere does not slow it down much, though smaller bodies can be substantially slowed by atmospheric drag, as they have a higher ratio of surface area to mass. In any case, the temperatures and pressures on the object are extremely high. These temperature and pressure extremes can destroy chondritic or carbonaceous chondritic bodies before they ever reach ground, but metallic iron-nickel meteorites have more structural integrity and can strike the surface of the Earth in a violent explosion. Chondrules in the chondrite Grassland. ...
Some carbonaceous chondrites. ...
When the object hits, it compresses a column of air, water and rock into an extremely hot plasma. This plasma expands violently, and cools rapidly (i.e. it explodes). The plasma and other ejecta splashes at orbital or near-orbital speeds. It can be thrown off into space, or can travel several times around the planet before re-entering as secondary meteors. Airless planets usually preserve stains of the ejecta around impact craters as a pattern of "rays". It should be noted that other non-impact theories for crater-ray formation have been suggested in the scientific literature. A Plasma lamp In physics and chemistry, a plasma is an ionized gas, and is usually considered to be a distinct phase of matter. ...
 Multi-ringed crater Valhalla on Jupiter's moon Callisto Very energetic chemistry occurs in the plasma. In an Earth impact, powerful acids can be formed from saltwater and air. The vaporized rock of the plasma condenses into characteristic cone-shaped droplets of glass called tektites, and these are widely distributed by the high speeds. Tektites are found in isolated strewnfields on Earth. Note: Several researchers reject the popular impact-origin theory of tektites based on comparisons to bonafide impactite glasses. Curiously, the largest and youngest (700,000 years ago) tektite strewnfield, known as the Australasian field, has no known crater associated with it; this fact strongly suggests that, at least in this case, the tektites are not linked to an impact. A giant "fresh" impact site, less than a million years old, should be visible on land or in the sea. No such Asian impact crater has ever been found.. Download high resolution version (1196x714, 370 KB)Valhalla crater on Callisto. ...
Download high resolution version (1196x714, 370 KB)Valhalla crater on Callisto. ...
A tektite Tektites (from Greek tektos, molten) are natural glass objects, up to a few centimeters in size, which — according to most scientists — have been formed by the impact of large meteorites on Earths surface, although a few researchers favor an origin from the Moon as volcanic ejecta. ...
Oceanic impacts can be considerably more damaging than those on land. Large objects will invariably penetrate or displace the water to impact the seabed, causing huge tsunamis over a large area. The impact at Chicxulub, Yucatán is believed to have produced tsunamis 50 to 100 metres (150-300 feet) high which deposited debris many miles inland. The tsunami that struck Malé in the Maldives on December 26, 2004. ...
Chicxulub (pronounced as CHEEK-shoe-lube) is a town in the state of Yucatán, Mexico, located at 21°14′ N 89°51′ W In 2000 the town had a population of about 3,400 people. ...
The result of an impact on land or at sea is a crater. There are two forms, "simple" and "complex". The Barringer crater in Arizona is a perfect example of a simple crater, a straightforward bowl in the ground. Simple craters are generally less than four kilometers across. The Barringer Crater, also known as the Meteor Crater, is a famous impact crater created by a meteorite, located about 55 kilometers east of Flagstaff in the northern Arizona desert (USA). ...
State nickname: The Grand Canyon State, The Copper State Other U.S. States Capital Phoenix Largest city Phoenix Governor Janet Napolitano (D) Official languages English Only State Area 295,254 km² (6th) - Land 294,312 km² - Water 942 km² (0. ...
Complex craters are larger, and have uplifted centers that are surrounded by a trough, plus broken rims. The uplifted center is due to the "rebound" of the earth after the impact. It is something like the ripple pattern created by a drop of water into a pool, frozen into the Earth when the melted rock cooled and solidified.
 Giant impact crater on Saturn's moon Mimas In either case, the size of the crater depends on the size of the impactor and the material in the impact regions. Relatively soft materials yield smaller craters than brittle materials. The size of craters invariably changes over time; in the short term, craters shrink as a result of slumping, and over the longer term erosion and other geological processes quickly hide impact craters on the Earth. The Barringer Crater is one of the best-preserved on the planet, but it is only about 50,000 years old. There are almost no signs of the 65 million year-old Chicxulub crater on the Earth's surface, despite it being one of the largest known on the planet. Image File history File links Mimas, Saturns moon. ...
Look up Erosion in Wiktionary, the free dictionary Severe soil erosion in a wheat field near Washington State University, USA. Erosion is the displacement of solids (soil, mud, rock, and so forth) by the agents of wind, water, ice, movement in response to gravity, or living organisms (in the case...
Some volcanic features can resemble impact craters, and brecciated rocks are associated with other geological formations besides impact craters. Non-explosive volcanic craters can usually be distinguished from impact craters by their irregular shape and the association of volcanic flows and other volcanic materials. An exception is that impact craters on Venus often have associated flows of melted material. Breccia, derived from the Latin word for broken, is a sedimentary rock composed of angular fragments in a matrix that may be of a similar or a different material. ...
The distinctive mark of an impact crater is the presence of rock that has undergone shock-metamorphic effects, such as shatter cones, melted rocks, and crystal deformations. The problem is that these materials tend to be deeply buried, at least for simple craters. They tend to be revealed in the uplifted center of a complex crater, however.
Impacts produce distinctive "shock-metamorphic" effects that allow impact sites to be distinctively identified. Such shock-metamorphic effects can include:
- A layer of shattered or "brecciated" rock under the floor of the crater. This layer is called a "breccia lens".
- Shatter cones, which are chevron-shaped impressions in rocks. Such cones are formed most easily in fine-grained rocks.
- High-temperature rock types, including laminated and welded blocks of sand, and tektites, or glassy spatters of molten rock. The impact origin of tektites has been questioned by some researchers; they have observed some volcanic features in tektites not found in impactites. Tektites are also drier (contain less water) than typical impactites. While rocks melted by the impact resemble volcanic rocks, they incorporate unmelted fragments of bedrock, form unusually large and unbroken fields, and have a much more mixed chemical composition than volcanic materials spewed up from within the Earth. They also may have relatively large amounts of trace elements that are associated with meteorites, such as nickel, platinum, iridium, and cobalt. Note: it is reported in the scientific literature that some "shock" features, such as small shatter cones, which are often reported as being associated only with impact events, have been found in terrestrial volcanic ejecta.
- Microscopic pressure deformations of minerals. These include fracture patterns in crystals of quartz and feldspar, and formation of high-pressure materials such as diamond, derived from graphite and other carbon compounds, or stishovite and coesite, varieties of shocked quartz.
Craters can also be created from underground nuclear explosions. One of the most crater-pocked sites on the planet is the Nevada Test Site, where a number of craters were purposely made during its years as a center for nuclear testing (see, for example, Operation Plowshare). Breccia, derived from the Latin word for broken, is a sedimentary rock composed of angular fragments in a matrix that may be of a similar or a different material. ...
A tektite Tektites (from Greek tektos, molten) are natural glass objects, up to a few centimeters in size, which — according to most scientists — have been formed by the impact of large meteorites on Earths surface, although a few researchers favor an origin from the Moon as volcanic ejecta. ...
Coesite is a form of silicon dioxide that is formed when very high pressure (2–3 gigapascals) and moderately high temperature (700 °C) are applied to quartz. ...
Shocked quartz is a form of quartz that has a microscopic structure that is different from normal quartz. ...
The mushroom cloud of the atomic bombing of Nagasaki, Japan, 1945, rose some 18 km (11 mi) above the epicenter. ...
The Nevada Test Site is a United States Department of Energy reservation located in Nye County, Nevada, about 65 miles (105 km) northwest of the City of Las Vegas, near 37°07′ N 116°03′ W. Formerly known as the Nevada Proving Ground the site, established on January 11, 1951...
A nuclear test explosion is an experiment involving the detonation of a nuclear weapon. ...
The 1962 Sedan plowshares shot displaced 12 million tons of earth and created a crater 320 feet deep and 1,280 feet wide. ...
Crater categorization In 1978, Chuck Wood and Leif Andersson of the Lunar & Planetary Lab devised a system of categorization of lunar impact craters. They used a sampling of craters that were relatively unmodified by subsequent impacts, then grouped the results into five broad categories. These successfully accounted for about 99% of all lunar impact craters. 1978 was a common year starting on Sunday (the link is to a full 1978 calendar). ...
The LPC Crater Types were as follows:
- ALC — small, cup-shaped craters with a diameter of about 10 km or less, and no central floor. The archetype for this category is 'Albategnius C'.
- BIO — similar to an ALC, but with small, flat floors. Typical diameter is about 15 km. The lunar crater archetype is Biot.
- SOS — the interior floor is wide and flat, with no central peak. The inner walls are not terraced. The diameter is normally in the range of 15-25 km. The archetype is Sosigenes crater.
- TRI — these complex craters are large enough so that their inner walls have slumped to the floor. They can range in size from 15-50 km in diameter. The archetype crater is Triesnecker.
- TYC — these are larger than 50 km, with terraced inner walls and relatively flat floors. They frequently have large central peak formations. Tycho crater is the archetype for this class.
Beyond a couple of hundred kilometers diameter, the central peak of the TYC class disappear and they are classed as basins. Archetype is defined as the original model of which all other similar persons, objects, or concepts are merely derivative, copied, patterned, or emulated. ...
Albategnius is an ancient lunar impact crater located in the central highlands. ...
Biot is a small, bowl-shaped lunar crater located in the southern reaches of the Mare Fecunditatis. ...
A terrace is: In agriculture, a levelled section of a hilly cultivated area, designed to slow or prevent the rapid run-off of irrigation water. ...
Sosigenes is a lunar impact crater on the west edge of Mare Tranquillitatis. ...
Triesnecker is a prominent lunar impact crater that is located in the Sinus Medii, near the central part of the Moons near side. ...
A terrace is: In agriculture, a levelled section of a hilly cultivated area, designed to slow or prevent the rapid run-off of irrigation water. ...
Tycho is a prominent lunar impact crater located in the southern lunar highlands. ...
Lists of craters The following is a (partial) list of identified impact craters on Earth, in order of size. ...
This is a list of named craters on Mercury. ...
This is a list of the craters on the Moon. ...
There are hundreds of thousands of craters on Mars, but only some of them have names. ...
This is a list of geological features on Phobos and Deimos, the moons of Mars. ...
In addition to the large Galilean moons, Jupiter is orbited by nearly sixty smaller moons, but only two of them, Amalthea and Thebe, have been imaged at sufficient resolution for surface features to become apparent. ...
The surface of Jupiters moon, Europa, is very young, geologically speaking, and as a result there are very few craters. ...
Ganymede is the largest moon in the solar system, and thus has many craters covering its hard surface. ...
Callisto is the most heavily cratered moon in the solar system. ...
This is list of named geological features on Janus, Epimetheus and Phoebe. ...
This is a list of named geological features on Mimas. ...
This is a list of named geological features on Enceladus. ...
This is a list of named geological features on Tethys. ...
This is a list of named geological features on Dione. ...
This is a list of named geological features on Rhea. ...
This is a list of named geological features on Iapetus. ...
This is a list of named craters on Puck. ...
This is a list of named geological features on Miranda. ...
This is a list of named geological features on Ariel. ...
This is a list of named craters on Umbriel. ...
This is a list of named geological features on Titania. ...
This is a list of named geological features (mostly craters) on Oberon. ...
This is a list of named geological features, of various kinds, on Triton. ...
Notable impact craters on Earth See the Earth Impact Database, a website concerned with over 160 identified impact craters on the Earth. The Barringer Crater, also known as the Meteor Crater, is a famous impact crater created by a meteorite, located about 55 kilometers east of Flagstaff in the northern Arizona desert (USA). ...
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Carolina bays are oval-shaped depressions found in coastal North Carolina, South Carolina, and northeastern Georgia. ...
The Chesapeake Bay Impact Crater was formed by the impact of an extraterrestrial bolide that hit about 35. ...
Radar topography reveals the 180 kilometer (112 mile) wide ring of the crater (image courtesy NASA/JPL-Caltech) Chicxulub Crater is an ancient impact crater buried underneath the Yucatan peninsula, with its center located approximately underneath the town of Chicxulub, Yucatán, Mexico. ...
Synthetic aperture radar image of Haughton crater The Haughton impact crater is located on Devon Island, Nunavut, Canada. ...
Lonar is a meteor crater in India. ...
Mahuika crater is a submarine bolide impact crater, 20±2 kilometers wide and over 153 meters deep, on the New Zealand continental shelf at 48. ...
Lake Manicouagan as seen from Earth orbit. ...
The Manson impact crater is located near the site of Manson, Iowa where a meteorite landed during the Cretaceous Period, 74 million years ago. ...
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Mistastin Lake crater. ...
The Nördlinger Ries is a depression in western Bavaria, Germany, located north of the Danube in the district of Donau-Ries. ...
Catskill Escarpment and Blackhead Range as seen from Overlook Mountain The Catskill Mountains, a natural area in New York State northwest of New York City and southwest of Albany, are not, despite their popular name, true geological mountains, but rather a mature dissected plateau, an uplifted region that was subsequently...
State nickname: Empire State Other U.S. States Capital Albany Largest city New York Governor George Pataki (R) Official languages None (English is de facto) Area 141,205 km² (27th) - Land 122,409 km² - Water 18,795 km² (13. ...
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Rochechouart is a meteor crater in France. ...
Sudbury Basin is the oval structure, next to the much younger lake-filled Wanapitei crater The Sudbury Basin is the second largest impact crater on earth, and a major geologic structure in Ontario, Canada. ...
Approximate location of the Silverpit crater The Silverpit crater is located in the North Sea off the coast of the United Kingdom. ...
The North Sea is a sea of the Atlantic Ocean, located between the coasts of Norway and Denmark in the east, the coast of the British Isles in the west, and the German, Dutch, Belgian and French coasts in the south. ...
The Rio Cuarto craters are a group of depressions located in Argentina at lattitude S 32° 52, longitude W 64° 14 There is currently some controversy as to whether these structures are actually produced by impacts, or by aeolian surficial processes, which form many similar features in that region; this...
Siljan, in Dalecarlia in central Sweden, is Swedens sixth largest lake. ...
Vredefort is a meteor crater in the Free State Province of South Africa. ...
Vredefort is a small mixed farming town in the Free State Province of South Africa with cattle, groundnuts, sorghum, sunflowers and maize being farmed. ...
The 19 km-diameter (12 mi) circular Weaubleau-Osceola structure is discernable in the drainage patterns of this shaded-relief image. ...
Some extraterrestrial craters The Caloris Basin, also called Caloris Planitia, is an impact crater, on Mercury, which is ~1350km in diameter. ...
For additional meanings, see Mercury (disambiguation). ...
NASA image of Hellas Planitia Hellas Planitia, also known as the Hellas Impact Basin, is a roughly circular impact crater located in the southern hemisphere of the planet Mars. ...
Mars is the fourth planet from the Sun in the solar system, named after the Roman god of war (the counterpart of the Greek Ares), on account of its blood red color as viewed in the night sky. ...
1967 photograph made by NASAs Lunar Orbiter 4 Like a target ring bulls-eye, the lunar mare Mare Orientale (the eastern sea) is one of the most striking large scale lunar features. ...
Crust composition Oxygen 43% Silicon 21% Aluminium 10% Calcium 9% Iron 9% Magnesium 5% Titanium 2% Nickel 0. ...
Petrach is a crater on Mercury. ...
The South Pole-Aitken basin is an impact crater on Earths Moon. ...
Herschel is a huge crater on the Saturnian moon Mimas. ...
Mimas (mye-mus) is a moon of Saturn that was discovered in 1789 by William Herschel. ...
References 1978 was a common year starting on Sunday (the link is to a full 1978 calendar). ...
See also Crater Lake, Oregon A caldera is a volcanic feature formed by the collapse of a volcano into itself. ...
The Cretaceous-Tertiary (K-T or KT) extinction event, also known as the KT boundary, was a period of massive extinction of species, about 65. ...
Artists impression of a major impact event. ...
Nemesis is the name given to a hypothetical red dwarf star or brown dwarf, magnitude at least 7, orbiting the Sun at a distance of about 50,000 to 100,000 AU, somewhat beyond the Oort cloud. ...
Crater ray system on the far side of the Moon. ...
Look up depth in Wiktionary, the free dictionary In classical physics, depth is a distance measured vertically from top to bottom (height) or horizontally from outside to inside (thickness). ...
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