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Crater Counting
Crater counting is a method for estimating the age of a planet's surface based upon the assumptions that when a piece of planetary surface is new, then it has no impact craters; impact craters accumulate after that at a rate that is assumed known. Consequently, counting how many craters of various sizes there are in a given area allows determining how long they have accumulated and, consequently, how long ago the surface has formed. The method has been calibrated using the ages obtained by radiometric dating of samples returned from the Moon by the Luna and Apollo missions. It has been used to estimate the age of areas on Mars and other planets that were covered by lava flows, on the Moon of areas covered by giant mares, and how long ago areas on the icy moons of Jupiter and Saturn flooded with new ice. Crater counting and secondary craters The crater counting method requires the presence of independent craters. Independent craters represent the primary impact point on a planets su ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Low Shield Volcano On Mars With Crater Counting
Low or LOW or lows, may refer to: People * Low (surname), listing people surnamed Low Places * Low, Quebec, Canada * Low, Utah, United States * Lo Wu station (MTR code LOW), Hong Kong; a rail station * Salzburg Airport (ICAO airport code: LOWS), Austria Music * Low (band), an American indie rock group from Duluth, Minnesota Albums * ''Low'' (David Bowie album), 1977 * ''Low'' (Testament album), 1994 * ''Low'' (Low EP), 1994 Songs * "Low" (Cracker song), 1993 * "Low" (Flo Rida song), 2007 * "Low" (Foo Fighters song), 2002 * "Low" (Juicy J song), 2014 * "Low" (Kelly Clarkson song), 2003 * "Low" (Lenny Kravitz song), 2018 * "Low" (Sara Evans song), 2008 * "Low", by Camp Mulla * "Low", by Coldplay from '' X&Y'' * "Low", by Inna from the self-titled album * "Low", by Marianas Trench from ''Fix Me'' * "Low", by R.E.M. from '' Out of Time'' * "Low", by Silverchair from ''Young Modern'' * "Low", by Sleeping with Sirens from ''Feel'' * "Low", by Tech N9ne from '' K.O.D.'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eugene Merle Shoemaker
Eugene Merle Shoemaker (April 28, 1928 – July 18, 1997) was an American geologist. He co-discovered Comet Shoemaker–Levy 9 with his wife Carolyn S. Shoemaker and David H. Levy. This comet hit Jupiter in July 1994: the impact was televised around the world. Shoemaker also studied terrestrial craters, such as Barringer Meteor Crater in Arizona, and along with Edward Chao provided the first conclusive evidence of its origin as an impact crater. He was also the first director of the United States Geological Survey's Astrogeology Research Program. He was killed in a car accident while visiting an impact crater site in Australia. After his death, some of his ashes were carried to the Moon with the Lunar Prospector mission. Early life and formal education Shoemaker was born in Los Angeles, California, the son of Muriel May (née Scott), a teacher; and George Estel Shoemaker, who worked in farming, business, teaching, and motion pictures. His parents were natives of Nebraska. D ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Formation And Evolution Of The Solar System
The formation of the Solar System began about 4.6 billion years ago with the gravitational collapse of a small part of a giant molecular cloud. Most of the collapsing mass collected in the center, forming the Sun, while the rest flattened into a protoplanetary disk out of which the planets, moons, asteroids, and other small Solar System bodies formed. This model, known as the nebular hypothesis, was first developed in the 18th century by Emanuel Swedenborg, Immanuel Kant, and Pierre-Simon Laplace. Its subsequent development has interwoven a variety of scientific disciplines including astronomy, chemistry, geology, physics, and planetary science. Since the dawn of the space age in the 1950s and the discovery of extrasolar planets in the 1990s, the model has been both challenged and refined to account for new observations. The Solar System has evolved considerably since its initial formation. Many moons have formed from circling discs of gas and dust around their parent planets ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glossary Of Meteoritics
This is a glossary of terms used in meteoritics, the science of meteorites. # * 2 Pallas – an asteroid from the asteroid belt and one of the likely parent bodies of the CR meteorites. * 4 Vesta – second-largest asteroid in the asteroid belt and likely source of the HED meteorites. * 221 Eos – an asteroid from the asteroid belt and one of the likely parent bodies of the CO meteorites. * 289 Nenetta – an asteroid from the asteroid belt and one of the likely parent bodies of the angrites. * 3103 Eger – an asteroid from the asteroid belt and one of the likely parent bodies of the aubrites. * 3819 Robinson – an asteroid from the asteroid belt and one of the likely parent bodies of the angrites. * IA meteorite – an iron meteorite group now part of the IAB group/complex. * IAB meteorite – an iron meteorite and primitive achondrite of the IAB group/complex. * IB meteorite – an iron meteorite group now part of the IAB group/complex. * IC meteorite – an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Meteorite
A meteorite is a solid piece of debris from an object, such as a comet, asteroid, or meteoroid, that originates in outer space and survives its passage through the atmosphere to reach the surface of a planet or Natural satellite, moon. When the original object enters the atmosphere, various factors such as friction, pressure, and chemical interactions with the atmospheric gases cause it to heat up and radiate energy. It then becomes a meteor and forms a Meteoroid#Fireball, fireball, also known as a shooting star; astronomers call the brightest examples "Bolide#Astronomy, bolides". Once it settles on the larger body's surface, the meteor becomes a meteorite. Meteorites vary greatly in size. For geologists, a bolide is a meteorite large enough to create an impact crater. Meteorites that are recovered after being observed as they transit the atmosphere and Impact event, impact the Earth are called meteorite falls. All others are known as meteorite finds. Meteorites have traditiona ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves. Absolute geochronology can be accomplished through radioactive isotopes, whereas relative geochronology is provided by tools such as paleomagnetism and stable isotope ratios. By combining multiple geochronological (and biostratigraphic) indicators the precision of the recovered age can be improved. Geochronology is different in application from biostratigraphy, which is the science of assigning sedimentary rocks to a known geological period via describing, cataloging and comparing fossil floral and faunal assemblages. Biostratigraphy does not ''directly'' provide an absolute age determination of a rock, but merely places it within an ''interval'' of time at which that fossil assemblage is known to have coexisted. Both disciplines work together hand in hand, however, to the point where they share the same system of naming strata (rock layers) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Secondary Crater
Secondary craters are impact craters formed by the ejecta that was thrown out of a larger crater. They sometimes form radial crater chains. In addition, secondary craters are often seen as clusters or rays surrounding primary craters. The study of secondary craters exploded around the mid-twentieth century when researchers studying surface craters to predict the age of planetary bodies realized that secondary craters contaminated the crater statistics of a body's crater count. Formation When a velocity-driven extraterrestrial object impacts a relatively stationary body, an impact crater forms. Initial crater(s) to form from the collision are known as primary craters or impact craters. Material expelled from primary craters may form secondary craters (secondaries) under a few conditions: # Primary craters must already be present. # The gravitational acceleration of the extraterrestrial body must be great enough to drive the ejected material back toward the surface. # The velocity b ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Impact Field Studies Group
The Impact Field Studies Group (IFSG) was a scientific organization emphasizing geologic field research of suspected and confirmed sites of impact craters and impact structures. The group is composed of researchers, professionals and students involved in study of impact sites. IFSG's web site is hosted by the Department of Earth and Planetary Sciences at University of Tennessee, Knoxville. Impact Database IFSG member David Rajmon maintains for the organization a list which was originally called the Suspected Earth Impact Sites (SEIS) list from 2004 to 2009. It was then renamed to simply the Impact Database. The list classifies impact sites as confirmed, most probable, probable, possible, improbable, rejected and proposed (unevaluated). The list retains rejected entries because they tend to be submitted repeatedly. The IFSG Impact Database accepts submissions of proposed new impact sites. However, they require submitters do some significant homework as listed below first. * T ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Aeolian Processes
Aeolian processes, also spelled eolian, pertain to wind activity in the study of geology and weather and specifically to the wind's ability to shape the surface of the Earth (or other planets). Winds may erode, transport, and deposit materials and are effective agents in regions with sparse vegetation, a lack of soil moisture and a large supply of unconsolidated sediments. Although water is a much more powerful eroding force than wind, aeolian processes are important in arid environments such as deserts. The term is derived from the name of the Greek god Aeolus, the keeper of the winds. Definition and setting ''Aeolian processes'' are those processes of erosion, transport, and deposition of sediments that are caused by wind at or near the surface of the earth. Sediment deposits produced by the action of wind and the sedimentary structures characteristic of these deposits are also described as ''aeolian''. Aeolian processes are most important in areas where there is little or ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Earth
Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surface is made up of the ocean, dwarfing Earth's polar ice, lakes, and rivers. The remaining 29% of Earth's surface is land, consisting of continents and islands. Earth's surface layer is formed of several slowly moving tectonic plates, which interact to produce mountain ranges, volcanoes, and earthquakes. Earth's liquid outer core generates the magnetic field that shapes the magnetosphere of the Earth, deflecting destructive solar winds. The atmosphere of the Earth consists mostly of nitrogen and oxygen. Greenhouse gases in the atmosphere like carbon dioxide (CO2) trap a part of the energy from the Sun close to the surface. Water vapor is widely present in the atmosphere and forms clouds that cover most of the planet. More solar e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tectonics
Tectonics (; ) are the processes that control the structure and properties of the Earth's crust and its evolution through time. These include the processes of mountain building, the growth and behavior of the strong, old cores of continents known as cratons, and the ways in which the relatively rigid plates that constitute the Earth's outer shell interact with each other. Tectonics also provide a framework for understanding the earthquake and volcanic belts that directly affect much of the global population. Tectonic studies are important as guides for economic geologists searching for fossil fuels and ore deposits of metallic and nonmetallic resources. An understanding of tectonic principles is essential to geomorphologists to explain erosion patterns and other Earth surface features. Main types of tectonic regime Extensional tectonics Extensional tectonics is associated with the stretching and thinning of the crust or the lithosphere. This type of tectonics is found ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geochronology
Geochronology is the science of determining the age of rocks, fossils, and sediments using signatures inherent in the rocks themselves. Absolute geochronology can be accomplished through radioactive isotopes, whereas relative geochronology is provided by tools such as paleomagnetism and stable isotope ratios. By combining multiple geochronological (and biostratigraphic) indicators the precision of the recovered age can be improved. Geochronology is different in application from biostratigraphy, which is the science of assigning sedimentary rocks to a known geological period via describing, cataloging and comparing fossil floral and faunal assemblages. Biostratigraphy does not ''directly'' provide an absolute age determination of a rock, but merely places it within an ''interval'' of time at which that fossil assemblage is known to have coexisted. Both disciplines work together hand in hand, however, to the point where they share the same system of naming strata (rock layers) and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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