1.
Mars
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Mars is the fourth planet from the Sun and the second-smallest planet in the Solar System, after Mercury. Named after the Roman god of war, it is referred to as the Red Planet because the iron oxide prevalent on its surface gives it a reddish appearance. Mars is a planet with a thin atmosphere, having surface features reminiscent both of the impact craters of the Moon and the valleys, deserts, and polar ice caps of Earth. The rotational period and seasonal cycles of Mars are likewise similar to those of Earth, Mars is the site of Olympus Mons, the largest volcano and second-highest known mountain in the Solar System, and of Valles Marineris, one of the largest canyons in the Solar System. The smooth Borealis basin in the northern hemisphere covers 40% of the planet, Mars has two moons, Phobos and Deimos, which are small and irregularly shaped. These may be captured asteroids, similar to 5261 Eureka, a Mars trojan, there are ongoing investigations assessing the past habitability potential of Mars, as well as the possibility of extant life. Future astrobiology missions are planned, including the Mars 2020 and ExoMars rovers, liquid water cannot exist on the surface of Mars due to low atmospheric pressure, which is about 6⁄1000 that of the Earths, except at the lowest elevations for short periods. The two polar ice caps appear to be largely of water. The volume of ice in the south polar ice cap, if melted. On November 22,2016, NASA reported finding a large amount of ice in the Utopia Planitia region of Mars. The volume of water detected has been estimated to be equivalent to the volume of water in Lake Superior, Mars can easily be seen from Earth with the naked eye, as can its reddish coloring. Its apparent magnitude reaches −2.91, which is surpassed only by Jupiter, Venus, the Moon, optical ground-based telescopes are typically limited to resolving features about 300 kilometers across when Earth and Mars are closest because of Earths atmosphere. Mars is approximately half the diameter of Earth with an area only slightly less than the total area of Earths dry land. Mars is less dense than Earth, having about 15% of Earths volume and 11% of Earths mass, the red-orange appearance of the Martian surface is caused by iron oxide, or rust. It can look like butterscotch, other common colors include golden, brown, tan. Like Earth, Mars has differentiated into a metallic core overlaid by less dense materials. Current models of its interior imply a core with a radius of about 1,794 ±65 kilometers, consisting primarily of iron and this iron sulfide core is thought to be twice as rich in lighter elements than Earths. The core is surrounded by a mantle that formed many of the tectonic and volcanic features on the planet
2.
NASA
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President Dwight D. Eisenhower established NASA in 1958 with a distinctly civilian orientation encouraging peaceful applications in space science. The National Aeronautics and Space Act was passed on July 29,1958, disestablishing NASAs predecessor, the new agency became operational on October 1,1958. Since that time, most US space exploration efforts have led by NASA, including the Apollo Moon landing missions, the Skylab space station. Currently, NASA is supporting the International Space Station and is overseeing the development of the Orion Multi-Purpose Crew Vehicle, the agency is also responsible for the Launch Services Program which provides oversight of launch operations and countdown management for unmanned NASA launches. NASA shares data with various national and international such as from the Greenhouse Gases Observing Satellite. Since 2011, NASA has been criticized for low cost efficiency, from 1946, the National Advisory Committee for Aeronautics had been experimenting with rocket planes such as the supersonic Bell X-1. In the early 1950s, there was challenge to launch a satellite for the International Geophysical Year. An effort for this was the American Project Vanguard, after the Soviet launch of the worlds first artificial satellite on October 4,1957, the attention of the United States turned toward its own fledgling space efforts. This led to an agreement that a new federal agency based on NACA was needed to conduct all non-military activity in space. The Advanced Research Projects Agency was created in February 1958 to develop technology for military application. On July 29,1958, Eisenhower signed the National Aeronautics and Space Act, a NASA seal was approved by President Eisenhower in 1959. Elements of the Army Ballistic Missile Agency and the United States Naval Research Laboratory were incorporated into NASA, earlier research efforts within the US Air Force and many of ARPAs early space programs were also transferred to NASA. In December 1958, NASA gained control of the Jet Propulsion Laboratory, NASA has conducted many manned and unmanned spaceflight programs throughout its history. Some missions include both manned and unmanned aspects, such as the Galileo probe, which was deployed by astronauts in Earth orbit before being sent unmanned to Jupiter, the experimental rocket-powered aircraft programs started by NACA were extended by NASA as support for manned spaceflight. This was followed by a space capsule program, and in turn by a two-man capsule program. This goal was met in 1969 by the Apollo program, however, reduction of the perceived threat and changing political priorities almost immediately caused the termination of most of these plans. NASA turned its attention to an Apollo-derived temporary space laboratory, to date, NASA has launched a total of 166 manned space missions on rockets, and thirteen X-15 rocket flights above the USAF definition of spaceflight altitude,260,000 feet. The X-15 was an NACA experimental rocket-powered hypersonic research aircraft, developed in conjunction with the US Air Force, the design featured a slender fuselage with fairings along the side containing fuel and early computerized control systems
3.
Jet Propulsion Laboratory
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The Jet Propulsion Laboratory is a federally funded research and development center and NASA field center in La Cañada Flintridge, California and Pasadena, California, United States. The JPL is managed by the nearby California Institute of Technology for NASA, the laboratorys primary function is the construction and operation of planetary robotic spacecraft, though it also conducts Earth-orbit and astronomy missions. It is also responsible for operating NASAs Deep Space Network and they are also responsible for managing the JPL Small-Body Database, and provides physical data and lists of publications for all known small Solar System bodies. The JPLs Space Flight Operations Facility and Twenty-Five-Foot Space Simulator are designated National Historic Landmarks, JPL traces its beginnings to 1936 in the Guggenheim Aeronautical Laboratory at the California Institute of Technology when the first set of rocket experiments were carried out in the Arroyo Seco. Malinas thesis advisor was engineer/aerodynamicist Theodore von Kármán, who arranged for U. S. Army financial support for this GALCIT Rocket Project in 1939. In 1941, Malina, Parsons, Forman, Martin Summerfield, in 1943, von Kármán, Malina, Parsons, and Forman established the Aerojet Corporation to manufacture JATO motors. The project took on the name Jet Propulsion Laboratory in November 1943, during JPLs Army years, the laboratory developed two deployed weapon systems, the MGM-5 Corporal and MGM-29 Sergeant intermediate range ballistic missiles. These missiles were the first US ballistic missiles developed at JPL and it also developed a number of other weapons system prototypes, such as the Loki anti-aircraft missile system, and the forerunner of the Aerobee sounding rocket. At various times, it carried out testing at the White Sands Proving Ground, Edwards Air Force Base. A lunar lander was developed in 1938-39 which influenced design of the Apollo Lunar Module in the 1960s. The team lost that proposal to Project Vanguard, and instead embarked on a project to demonstrate ablative re-entry technology using a Jupiter-C rocket. They carried out three successful flights in 1956 and 1957. Using a spare Juno I, the two organizations then launched the United States first satellite, Explorer 1, on February 1,1958, JPL was transferred to NASA in December 1958, becoming the agencys primary planetary spacecraft center. JPL engineers designed and operated Ranger and Surveyor missions to the Moon that prepared the way for Apollo, JPL also led the way in interplanetary exploration with the Mariner missions to Venus, Mars, and Mercury. In 1998, JPL opened the Near-Earth Object Program Office for NASA, as of 2013, it has found 95% of asteroids that are a kilometer or more in diameter that cross Earths orbit. JPL was early to employ women mathematicians, in the 1940s and 1950s, using mechanical calculators, women in an all-female computations group performed trajectory calculations. In 1961, JPL hired Dana Ulery as their first woman engineer to work alongside male engineers as part of the Ranger and Mariner mission tracking teams, when founded, JPLs site was a rocky flood-plain just outside the city limits of Pasadena. Almost all of the 177 acres of the U. S, the city of La Cañada Flintridge, California was incorporated in 1976, well after JPL attained international recognition with a Pasadena address
4.
Cape Canaveral Air Force Station
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Cape Canaveral Air Force Station is an installation of the United States Air Force Space Commands 45th Space Wing, headquartered at nearby Patrick Air Force Base. Located on Cape Canaveral in Brevard County, Florida, CCAFS is the primary head of Americas Eastern Range with three launch pads currently active. The Cape Canaveral Air Force Station Skid Strip provides a 10, 000-foot runway close to the launch complexes for military airlift aircraft delivering heavy, a number of American space exploration firsts were launched from CCAFS, including the first U. S. Earth satellite, first U. S. astronaut, first U. S. astronaut in orbit, first two-man U. S. spacecraft, first U. S. unmanned lunar landing, and first three-man U. S. spacecraft. The CCAFS area had used by the United States government to test missiles since 1949. On June 1,1948, the U. S. Navy transferred the former Banana River Naval Air Station to the U. S. Air Force, with USAF renaming the facility the Joint Long Range Proving Ground Base on June 10,1949. On October 1,1949, the Joint Long Range Proving Ground Base was transferred from the Air Materiel Command to the Air Force Division of the Joint Long Range Proving Ground. On May 17,1950, the base was renamed the Long Range Proving Ground Base, in 1951, the Air Force established the Air Force Missile Test Center. Early American sub-orbital rocket flights were achieved at Cape Canaveral in 1956 and these flights occurred shortly after sub-orbital flights launched from White Sands Missile Range, such as the Viking 12 sounding rocket on February 4,1955. Following the Soviet Unions successful Sputnik 1, the US attempted its first launch of a satellite from Cape Canaveral on December 6,1957. However, the rocket carrying Vanguard TV3 blew up on the launch pad, NASA was founded in 1958, and Air Force crews launched missiles for NASA from the Cape, known then as Cape Canaveral Missile Annex. The row of Titan and Atlas launch pads along the coast came to be known as Missile Row in the 1960s, nASAs first manned spaceflight program was prepared for launch from Canaveral by U. S. Air Force crews. Mercurys objectives were to place a spacecraft in Earth orbit, investigate human performance and ability to function in space. Suborbital flights were launched by derivatives of the Armys Redstone missile from LC-5, Orbital flights were launched by derivatives of the Air Forces larger Atlas D missile from LC-14. The first American in orbit was John Glenn on February 20,1962, three more orbital flights followed through May 1963. Flight control for all Mercury missions was provided at the Mercury Control Center located at Canaveral near LC-14 and he had also convinced Gov. C. Farris Bryant to change the name of Cape Canaveral to Cape Kennedy and this resulted in some confusion in public perception, which conflated the two. This name was used through the Gemini and early Apollo programs, however, the geographical name change proved to be unpopular, owing to the historical longevity of Cape Canaveral
5.
Equator
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The Equator usually refers to an imaginary line on the Earths surface equidistant from the North Pole and South Pole, dividing the Earth into the Northern Hemisphere and Southern Hemisphere. The Equator is about 40,075 kilometres long, some 78. 7% lies across water and 21. 3% over land, other planets and astronomical bodies have equators similarly defined. Generally, an equator is the intersection of the surface of a sphere with the plane that is perpendicular to the spheres axis of rotation. The latitude of the Earths equator is by definition 0° of arc, the equator is the only line of latitude which is also a great circle — that is, one whose plane passes through the center of the globe. The plane of Earths equator when projected outwards to the celestial sphere defines the celestial equator, in the cycle of Earths seasons, the plane of the equator passes through the Sun twice per year, at the March and September equinoxes. To an observer on the Earth, the Sun appears to travel North or South over the equator at these times, light rays from the center of the Sun are perpendicular to the surface of the Earth at the point of solar noon on the Equator. Locations on the Equator experience the quickest sunrises and sunsets because the sun moves nearly perpendicular to the horizon for most of the year. The Earth bulges slightly at the Equator, the diameter of the Earth is 12,750 kilometres. Because the Earth spins to the east, spacecraft must also launch to the east to take advantage of this Earth-boost of speed, seasons result from the yearly revolution of the Earth around the Sun and the tilt of the Earths axis relative to the plane of revolution. During the year the northern and southern hemispheres are inclined toward or away from the sun according to Earths position in its orbit, the hemisphere inclined toward the sun receives more sunlight and is in summer, while the other hemisphere receives less sun and is in winter. At the equinoxes, the Earths axis is not tilted toward the sun, instead it is perpendicular to the sun meaning that the day is about 12 hours long, as is the night, across the whole of the Earth. Near the Equator there is distinction between summer, winter, autumn, or spring. The temperatures are usually high year-round—with the exception of high mountains in South America, the temperature at the Equator can plummet during rainstorms. In many tropical regions people identify two seasons, the wet season and the dry season, but many places close to the Equator are on the oceans or rainy throughout the year, the seasons can vary depending on elevation and proximity to an ocean. The Equator lies mostly on the three largest oceans, the Pacific Ocean, the Atlantic Ocean, and the Indian Ocean. The highest point on the Equator is at the elevation of 4,690 metres, at 0°0′0″N 77°59′31″W and this is slightly above the snow line, and is the only place on the Equator where snow lies on the ground. At the Equator the snow line is around 1,000 metres lower than on Mount Everest, the Equator traverses the land of 11 countries, it also passes through two island nations, though without making a landfall in either. Starting at the Prime Meridian and heading eastwards, the Equator passes through, Despite its name, however, its island of Annobón is 155 km south of the Equator, and the rest of the country lies to the north
6.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
7.
Tharsis
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Tharsis is a vast volcanic plateau centered near the equator in the western hemisphere of Mars. The tallest volcano on the planet, Olympus Mons, is associated with the Tharsis region but is actually located off the western edge of the plateau. The name Tharsis is the Greco-Latin transliteration of the biblical Tarshish, Tharsis can have many meanings depending on historical and scientific context. The name is used in a broad sense to represent a continent-sized region of anomalously elevated terrain centered just south of the equator around longitude 265°E. Called the Tharsis bulge or Tharsis rise, this broad, elevated region dominates the western hemisphere of Mars and is the largest topographic feature on the planet, Tharsis has no formally defined boundaries, so precise dimensions for the region are difficult to give. In general, the bulge is about 5,000 km across and it roughly extends from Amazonis Planitia in the west to Chryse Planitia in the east. The bulge is slightly elongated in the direction, running from the northern flanks of Alba Mons to the southern base of the Thaumasia highlands. Depending on how the region is defined, Tharsis covers 10–30 million km2, the greater Tharsis region consists of several geologically distinct subprovinces with different ages and volcano-tectonic histories. The subdivisions given here are informal and may comprise all or parts of other formally named physiographic features, Tharsis is divided into two broad rises, a northern and a larger southern rise. The northern rise partially overlies sparsely cratered, lowland plains north of the dichotomy boundary and this region is dominated by Alba Mons and its extensive volcanic flows. Alba Mons is a vast, low-lying volcanic construct that is unique to Mars, Alba Mons is so large and topographically distinct that it can almost be treated as an entire volcanic province unto itself. The oldest part of the northern rise consists of a broad ridge that corresponds to the highly fractured terrain of Ceraunius Fossae. The ridge is oriented north-south and forms part of the Noachian-aged basement on which Alba Mons sits, the larger southern portion of Tharsis lies on old cratered highland terrain. Its western boundary is defined by the high lava plains of Daedalia Planum. To the east, the southern Tharsis bulge consists of the vast Syria-Thaumasia block, Syria-Thaumasia is bounded to the north by Noctis Labyrinthus and the western three-quarters of Valles Marineris. It is bounded to the east by a north-south oriented ridge called the Coprates rise and these boundaries enclose a broad high plateau and shallow interior basin that include Syria, Sinai, and Solis Plana. The highest plateau elevations on the Tharsis bulge occur in northern Syria Planum, western Noctis Labyrinthus, between the northern and southern portions of the Tharsis bulge lies a relatively narrow, northeast-trending region that may be considered Tharsis proper or central Tharsis. It is defined by the three massive Tharsis Montes volcanoes, a number of volcanic edifices, and adjacent plains consisting of young lava flows
8.
Valles Marineris
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Valles Marineris is a system of canyons that runs along the Martian surface east of the Tharsis region. At more than 4,000 km long,200 km wide and up to 7 km deep, Valles Marineris is one of the largest canyons of the Solar System, surpassed in length only by the rift valleys of Earth. Valles Marineris is located along the equator of Mars, on the east side of the Tharsis Bulge and it has been recently suggested that Valles Marineris is a large tectonic crack in the Martian crust. Most researchers agree that this formed as the crust thickened in the Tharsis region to the west, near the eastern flanks of the rift, there appear to be channels that may have been formed by water or carbon dioxide. It has also proposed that Valles Marineris is a large channel formed by the erosion of lava flowing from the flank of Pavonis Mons. There have been many different theories about the formation of Valles Marineris that have changed over the years, ideas in the 1970s were erosion by water or thermokarst activity, which is the melting of permafrost in glacial climes. Many scientists agree that there was liquid water flowing on the Martian surface in the past, Valles Marineris may have been enlarged by flowing water at this time. Another hypothesis by McCauley in 1972 was that the canyons formed by withdrawal of subsurface magma, around 1989 Tanaka and Golombek proposed a theory of formation by tensional fracturing. The most agreed upon theory today is that Valles Marineris was formed by rift faults like the East African Rift, later made bigger by erosion and it has also been proposed that Valles Marineris was formed by flowing lava. The formation of Valles Marineris is thought to be tied with the formation of the Tharsis Bulge. The Tharsis Bulge was formed from the Noachian to Late Hesperian period of Mars, stage two consisted of more volcanism and a loss of isostatic equilibrium, the source regions of the volcanism no longer resided underneath Tharsis, creating a very large load. Finally, the crust failed to hold up Tharsis and radial fractures formed, stage three mainly consisted of more volcanism and asteroid impacts. The crust, having reached its failure point, just stayed in place. Landslides have left numerous deposits on the floor of Valles Marineris, possible triggers of landslides are quakes caused by tectonic activity or impact events. Both types of events release seismic waves that accelerate the ground at, Mars is much less tectonically active than Earth, and Mars-quakes are unlikely to have provided seismic waves of the required magnitude. Most sizable craters on Mars date to the Late Heavy Bombardment,4.1 to 3.8 billion years ago, and are older than the landslide deposits in Valles Marineris. However, three craters have been identified, on the basis of their proximity and later dates, as ones whose formation may have caused some of the landslides, also it contains canyons that run in different directions surrounding large blocks of older terrain. Most of the parts of the blocks are composed of younger fractured material thought to be of volcanic origin associated with the Tharsis bulge
9.
Apollo 11
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Apollo 11 was the spaceflight that landed the first two humans on the Moon. Mission commander Neil Armstrong and pilot Buzz Aldrin, both American, landed the lunar module Eagle on July 20,1969, at 20,18 UTC. Armstrong became the first to step onto the lunar surface six hours later on July 21 at 02,56,15 UTC and they spent about two and a quarter hours together outside the spacecraft, and collected 47.5 pounds of lunar material to bring back to Earth. Michael Collins piloted the command module Columbia alone in lunar orbit while they were on the Moons surface, Armstrong and Aldrin spent just under a day on the lunar surface before rendezvousing with Columbia in lunar orbit. Apollo 11 was launched by a Saturn V rocket from Kennedy Space Center in Merritt Island, Florida, on July 16, and was the fifth manned mission of NASAs Apollo program. After being sent toward the Moon by the Saturn Vs upper stage, Armstrong and Aldrin then moved into the lunar module Eagle and landed in the Sea of Tranquility. They stayed a total of about 21.5 hours on the lunar surface, the astronauts used Eagles upper stage to lift off from the lunar surface and rejoin Collins in the command module. They jettisoned Eagle before they performed the maneuvers that blasted them out of orbit on a trajectory back to Earth. They returned to Earth and landed in the Pacific Ocean on July 24, broadcast on live TV to a worldwide audience, Armstrong stepped onto the lunar surface and described the event as one small step for man, one giant leap for mankind. Apollo 11 was the second all-veteran multi-person crew in human spaceflight history, a previous solo veteran flight had been made on Soyuz 1 in 1967 by Soviet cosmonaut Vladimir Komarov. Collins was originally slated to be the Command Module Pilot on Apollo 8 but was removed when he required surgery on his back and was replaced by Jim Lovell, his backup for that flight. In early 1969, Anders accepted a job with the National Space Council effective August 1969, charlie Duke, Capsule Communicator Ronald Evans Owen K. Garriott Don L. Low to suggest the Apollo 11 crew be less flippant in naming their craft. During early mission planning, the names Snowcone and Haystack were used and put in the news release, the Command Module was named Columbia after the Columbiad, the giant cannon shell spacecraft fired by a giant cannon in Jules Vernes 1865 novel From the Earth to the Moon. The Lunar Module was named Eagle for the bird of the United States, the bald eagle. The Apollo 11 mission insignia was designed by Collins, who wanted a symbol for peaceful lunar landing by the United States and he chose an eagle as the symbol, put an olive branch in its beak, and drew a lunar background with the Earth in the distance. NASA officials said the talons of the eagle looked too warlike and after some discussion, All colors are natural, with blue and gold borders around the patch. When the Eisenhower dollar coin was released in 1971, the design provided the eagle for its reverse side. The design was used for the smaller Susan B
10.
Ultraviolet
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Ultraviolet is an electromagnetic radiation with a wavelength from 10 nm to 400 nm, shorter than that of visible light but longer than X-rays. UV radiation constitutes about 10% of the light output of the Sun. It is also produced by electric arcs and specialized lights, such as lamps, tanning lamps. Consequently, the effects of UV are greater than simple heating effects. Suntan, freckling and sunburn are familiar effects of over-exposure, along with risk of skin cancer. Living things on dry land would be damaged by ultraviolet radiation from the Sun if most of it were not filtered out by the Earths atmosphere. More-energetic, shorter-wavelength extreme UV below 121 nm ionizes air so strongly that it is absorbed before it reaches the ground, Ultraviolet is also responsible for the formation of bone-strengthening vitamin D in most land vertebrates, including humans. The UV spectrum thus has both beneficial and harmful to human health. Ultraviolet rays are invisible to most humans, the lens in a human eye ordinarily filters out UVB frequencies or higher, and humans lack color receptor adaptations for ultraviolet rays. Under some conditions, children and young adults can see ultraviolet down to wavelengths of about 310 nm, near-UV radiation is visible to some insects, mammals, and birds. Small birds have a fourth color receptor for ultraviolet rays, this gives birds true UV vision, reindeer use near-UV radiation to see polar bears, who are poorly visible in regular light because they blend in with the snow. UV also allows mammals to see urine trails, which is helpful for animals to find food in the wild. The males and females of some species look identical to the human eye. Ultraviolet means beyond violet, violet being the color of the highest frequencies of visible light, Ultraviolet has a higher frequency than violet light. He called them oxidizing rays to emphasize chemical reactivity and to them from heat rays. The terms chemical and heat rays were eventually dropped in favour of ultraviolet and infrared radiation, in 1878 the effect of short-wavelength light on sterilizing bacteria was discovered. By 1903 it was known the most effective wavelengths were around 250 nm, in 1960, the effect of ultraviolet radiation on DNA was established. The discovery of the ultraviolet radiation below 200 nm, named vacuum ultraviolet because it is absorbed by air, was made in 1893 by the German physicist Victor Schumann
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