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Corona (planetary Geology)
In planetary geology, a corona (plural: coronae ) is an oval-shaped feature. Coronae appear on both the planet Venus and Uranus's moon Miranda and may be formed by upwellings of warm material below the surface. Coronae on Venus The geodynamic surface of Venus is dominated by patterns of basaltic volcanism, and by compressional and extensional tectonic deformation, such as the highly deformed tesserae terrain and the concentrically-fractured coronae. On Venus, coronae are large (typically several hundred kilometres across), crown-like, volcanic features. Coronae were first identified in 1983, when the radar imaging equipment aboard the Venera 15 and Venera 16 spacecraft produced higher-resolution images of some features previously thought to be impact craters. It is believed that coronae are formed when plumes of rising hot material in the mantle push the crust upwards into a dome shape, which then collapses in the centre as the molten magma cools and leaks out at the sid ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Planetary Geology
Planetary geology, alternatively known as astrogeology or exogeology, is a planetary science discipline concerned with the geology of celestial bodies such as planets and their moons, asteroids, comets, and meteorites. Although the geo- prefix typically indicates topics of or relating to Earth, planetary geology is named as such for historical and convenience reasons; due to the subject matter, it is closely linked with more traditional Earth-based geology. Planetary geology includes such topics as determining the properties and processes of the internal structure of the terrestrial planets, surface processes such as volcanism, impact craters, even fluvial and aeolian action where applicable. Despite their outermost layers being dominated by gases, the giant planets are also included in the field of planetary geology, especially when it comes to their interiors. Fields within Planetary geology are largely derived from fields in the traditional geological sciences, such as geoph ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oval
An oval () is a closed curve in a plane which resembles the outline of an egg. The term is not very specific, but in some areas of mathematics (projective geometry, technical drawing, etc.), it is given a more precise definition, which may include either one or two axes of symmetry of an ellipse. In common English, the term is used in a broader sense: any shape which reminds one of an egg. The three-dimensional version of an oval is called an ovoid. Oval in geometry The term oval when used to describe curves in geometry is not well-defined, except in the context of projective geometry. Many distinct curves are commonly called ovals or are said to have an "oval shape". Generally, to be called an oval, a plane curve should ''resemble'' the outline of an egg or an ellipse. In particular, these are common traits of ovals: * they are differentiable (smooth-looking), simple (not self-intersecting), convex, closed, plane curves; * their shape does not depart much from that of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venus
Venus is the second planet from the Sun. It is often called Earth's "twin" or "sister" planet for having almost the same size and mass, and the closest orbit to Earth's. While both are rocky planets, Venus has an atmosphere much thicker and denser than Earth and any other rocky body in the Solar System. Its atmosphere is composed of mostly carbon dioxide (), with a global sulfuric acid cloud cover and no liquid water. At the mean surface level the atmosphere reaches a temperature of and a pressure 92 times greater than Earth's at sea level, turning the lowest layer of the atmosphere into a supercritical fluid. Venus is the third brightest object in Earth's sky, after the Moon and the Sun, and, like Mercury, appears always relatively close to the Sun, either as a "morning star" or an "evening star", resulting from orbiting closer ( inferior) to the Sun than Earth. The orbits of Venus and Earth make the two planets approach each other in synodic periods of 1.6 years ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Uranus
Uranus is the seventh planet from the Sun. It is a gaseous cyan-coloured ice giant. Most of the planet is made of water, ammonia, and methane in a Supercritical fluid, supercritical phase of matter, which astronomy calls "ice" or Volatile (astrogeology), volatiles. Atmosphere of Uranus, The planet's atmosphere has a complex layered cloud structure and has the lowest minimum temperature () of all the Solar System's planets. It has a marked axial tilt of 82.23° with a Retrograde and prograde motion, retrograde rotation period of 17 hours and 14 minutes. This means that in an 84-Earth-year orbital period around the Sun, its poles get around 42 years of continuous sunlight, followed by 42 years of continuous darkness. Uranus has the third-largest diameter and fourth-largest mass among the Solar System's planets. Based on current models, inside its volatile Mantle (geology), mantle layer is a rocky core, and surrounding it is a thick hydrogen and helium atmosphere. Trace amount ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Miranda (moon)
Miranda, also designated Uranus V, is the smallest and innermost of Uranus's five round natural satellite, satellites. It was discovered by Gerard Kuiper on 16 February 1948 at McDonald Observatory in Texas, and named after Miranda (The Tempest), Miranda from William Shakespeare's play ''The Tempest''. Like the other large moons of Uranus, Miranda orbits close to its planet's equatorial plane. Because Uranus orbits the Sun on its side, Miranda's orbit is nearly perpendicular to the ecliptic and shares Uranus's extreme seasonal cycle. At just in diameter, Miranda is one of the smallest closely observed objects in the Solar System that might be in hydrostatic equilibrium (spherical under its own gravity), and its total surface area is roughly equal to that of the U.S. state of Texas. The only close-up images of Miranda are from the ''Voyager 2'' probe, which made observations of Miranda during its Uranus flyby in January 1986. During the flyby, Miranda's southern hemisphere po ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geodynamics Of Venus
NASA's Magellan spacecraft mission discovered that Venus has a geologically young surface with a relatively uniform age of 500±200 Ma (million years). The age of Venus was revealed by the observation of over 900 impact craters on the surface of the planet. These impact craters are nearly uniformly distributed over the surface of Venus and less than 10% have been modified by plains of volcanism or deformation. These observations indicate that a catastrophic resurfacing event took place on Venus around 500 Ma, and was followed by a dramatic decline in resurfacing rate. The radar images from the Magellan missions revealed that the terrestrial style of plate tectonics is not active on Venus and the surface currently appears to be immobile. Despite these surface observations, there are numerous surface features that indicate an actively convecting interior. The Soviet Venera landings revealed that the surface of Venus is essentially basaltic in composition based on geochemical measur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tessera (Venusian Geography)
A tessera (plural tesserae) is a region of heavily deformed terrain on Venus, characterized by two or more intersecting tectonic elements, high topography, and subsequent high radar backscatter. Tesserae often represent the oldest material at any given location and are among the most tectonically deformed terrains on Venus's surface. Diverse types of tessera terrain exist. It is not currently clear if this is due to a variety in the interactions of Venus's mantle with regional crustal or lithospheric stresses, or if these diverse terrains represent different locations in the timeline of crustal plateau formation and fall. Multiple models of tessera formation exist and further extensive studies of Venus's surface are necessary to fully understand this complex terrain. Exploration Pioneer Venus Orbiter detected regions of anomalous radar properties and high backscatter. Using SAR imaging, the Venera 15 and Venera 16 orbiters revealed these regions to be chaotically tiled terrain ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radar
Radar is a system that uses radio waves to determine the distance ('' ranging''), direction ( azimuth and elevation angles), and radial velocity of objects relative to the site. It is a radiodetermination method used to detect and track aircraft, ships, spacecraft, guided missiles, motor vehicles, map weather formations, and terrain. The term ''RADAR'' was coined in 1940 by the United States Navy as an acronym for "radio detection and ranging". The term ''radar'' has since entered English and other languages as an anacronym, a common noun, losing all capitalization. A radar system consists of a transmitter producing electromagnetic waves in the radio or microwave domain, a transmitting antenna, a receiving antenna (often the same antenna is used for transmitting and receiving) and a receiver and processor to determine properties of the objects. Radio waves (pulsed or continuous) from the transmitter reflect off the objects and return to the receiver, giving ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venera 15
Venera 15 ( meaning ''Venus 15'') was a spacecraft sent to Venus by the Soviet Union. This uncrewed orbiter was to map the surface of Venus using high resolution imaging systems. The spacecraft was identical to Venera 16 and based on modifications to the earlier Venera space probes. Mission profile Venera 15 was launched on June 2, 1983, at 02:38:39 UTC and reached Venus' orbit on October 10, 1983. The spacecraft was inserted into Venus orbit a day apart from Venera 16, with its orbital plane shifted by an angle of approximately 4° relative to the other probe. This made it possible to reimage an area if necessary. The spacecraft was in a nearly polar orbit with a periapsis ~1000 km, at 62°N latitude, and apoapsis ~65000 km, with an inclination ~90°, the orbital period being ~24 hours. Together with Venera 16, the spacecraft imaged the area from the north pole down to about 30°N latitude (approximately 25% of Venus surface) over the eight months of mapping opera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Venera 16
Venera 16 ( meaning ''Venus 16'') was a spacecraft sent to Venus by the Soviet Union. This uncrewed orbiter was to map the surface of Venus using high resolution imaging systems. The spacecraft was identical to Venera 15 and based on modifications to the earlier Venera space probes. The latest data from the spacecraft were received on June 13, 1985, when it responded to the signal sent from Earth for Vega 1. Mission profile Venera 16 was launched on June 7, 1983, at 02:32:00 UTC and reached Venus' orbit on October 11, 1983. The spacecraft was inserted into Venus orbit a day apart from Venera 15, with its orbital plane shifted by an angle of approximately 4° relative to one another probe. This made it possible to reimage an area if necessary. The spacecraft was in a nearly polar orbit with a periapsis of ~, at 62°N latitude, and an apoapsis of ~, with an inclination ~90°, the orbital period being ~24 hours. Together with Venera 15, the spacecraft imaged the area from the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Artemis Corona
Artemis Corona is a corona found in the Aphrodite Terra continent, on the planet Venus, at . Named after Artemis In ancient Greek religion and Greek mythology, mythology, Artemis (; ) is the goddess of the hunting, hunt, the wilderness, wild animals, transitions, nature, vegetation, childbirth, Kourotrophos, care of children, and chastity. In later tim ..., the Greek goddess of hunting, it is the largest corona on Venus, with a diameter of . First described in 1980, it is largely enclosed by the near circular Artemis Chasma a circular belt of arc-shaped features believed to be largely of compressional origin. Artemis is an unusual feature on Venus as it has been interpreted to be the site of plate tectonics operating on a regional scale. There are grabens and compressional arcs which rise above the surrounding plains. As a whole, Artemis is not elevated like other coronae. Regions within Artemis are in fact some below the surrounding plains. The differences between th ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
