1.
RBS 70
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RBS70 is a man-portable air-defense system designed for anti-aircraft warfare in all climate zones and with little to no support from other forces. Originally designed and manufactured by the Swedish defence firm of Bofors Defence and it uses the RB70 missile which is also in use in a number of other Swedish missile systems. The RBS70 was developed to supply the Swedish air defense with a low-cost, easy-to-use, before RBS70 the mainstay of Swedish air defense was American MIM-23 Hawk systems, American Redeye and the Swedish Bofors m/48 AAA. The Swedish Army has decided to replace the RBS70 with a version of the IRIS-T missile. The RBS70 is a Short-range Air Defense laser guided missile system, Mk 1 and Mk 2 followed shortly and are the standard RBS70 with a range of 5, 000–6,000 m and a ceiling of 3,000 m. Currently, RBS70 is operational in 18 customer countries, on all continents and in arctic, desert, in 2003 the BOLIDE upgrade system was introduced to the RBS70. The BOLIDE missile is an RBS70 Mk 2 upgrade that is faster, with a range up to 8 km, in 2011, Saab Bofors Dynamics announced the introduction of the new RBS70 New Generation. The upgraded version included a sighting system capable of night vision and improved training. In 1992, a Venezuelan Army RBS-70 SAM is attributed with having shot down a rebel OV-10 Bronco during the 1992 Venezuelan coup détat attempt on November 27
2.
Fireball (meteor)
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A meteoroid is a small rocky or metallic body in outer space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects, objects smaller than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars and this phenomenon is called a meteor or shooting star. A series of many meteors appearing seconds or minutes apart and appearing to originate from the fixed point in the sky is called a meteor shower. If that object withstands ablation from its passage through the atmosphere as a meteor and impacts with the ground, an estimated 15,000 tonnes of meteoroids, micrometeoroids and different forms of space dust enter Earths atmosphere each year. In 1995, Beech and Steel, writing in the Quarterly Journal of the Royal Astronomical Society, according to Rubin and Grossman, the minimum size of an asteroid is given by what can be discovered from Earth-bound telescopes, so the distinction between meteoroid and asteroid is fuzzy. Some of the smallest asteroids discovered are 2008 TS26 with H =33.2 and 2011 CQ1 with H =32.1 both with a size of 1 meter. Objects smaller than meteoroids are classified as micrometeoroids and cosmic dust, the Minor Planet Center does not use the term meteoroid. Almost all meteoroids contain extraterrestrial nickel and iron and they have three main classifications, iron, stone, and stony-iron. Some stone meteoroids contain grain-like inclusions known as chondrules and are called chondrites, stoney meteoroids without these features are called achondrites, which are typically formed from extraterrestrial igneous activity, they contain little or no extraterrestrial iron. The composition of meteoroids can be inferred as they pass through Earths atmosphere from their trajectories and their effects on radio signals also give information, especially useful for daytime meteors, which are otherwise very difficult to observe. From these trajectory measurements, meteoroids have been found to have many different orbits, some clustering in streams associated with a parent comet. Debris from meteoroid streams may eventually be scattered into other orbits, the study of meteorites also gives insights into the composition of non-ephemeral meteoroids. Most meteoroids come from the belt, having been perturbed by the gravitational influences of planets. Some meteoroids are pieces of planets or moons, such as Mars or our moon, meteoroids travel around the Sun in a variety of orbits and at various velocities. The fastest ones move at about 42 kilometers per second through space in the vicinity of Earths orbit, Earth travels at about 29.6 kilometers per second. Thus, when meteoroids meet Earths atmosphere head-on, the speed may reach about 71 kilometers per second. Meteoroids moving through Earths orbital space average about 20 km/s, on January 17,2013 at 05,21 PST, a 1 meter-sized comet from the Oort cloud entered Earth atmosphere over a wide area in California and Nevada
3.
Magnitude (astronomy)
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In astronomy, magnitude is a logarithmic measure of the brightness of an object, measured in a specific wavelength or passband, usually in the visible or near-infrared spectrum. An imprecise but systematic determination of the magnitude of objects was introduced in ancient times by Hipparchus, astronomers use two different definitions of magnitude, apparent magnitude and absolute magnitude. This distance is 10 parsecs for stars and 1 astronomical unit for planets, a minor planets size is typically estimated based on its absolute magnitude in combination with its presumed albedo. The brighter an object appears, the lower the value of its magnitude, with the brightest objects reaching negative values. The Sun has an apparent magnitude of −27, the full moon −13, the brightest planet Venus measures −5, and Sirius, an apparent magnitude can also be assigned to man-made objects in Earth orbit. The brightest satellite flares are ranked at −9, and the International Space Station, ISS, the scale is logarithmic, and defined such that each step of one magnitude changes the brightness by a factor of the fifth root of 100, or approximately 2.512. For example, a magnitude 1 star is exactly a hundred times brighter than a magnitude 6 star, the magnitude system dates back roughly 2000 years to the Greek astronomer Hipparchus who classified stars by their apparent brightness, which they saw as size. To the unaided eye, a prominent star such as Sirius or Arcturus appears larger than a less prominent star such as Mizar. For all the other Stars, which are seen by the Help of a Telescope. Note that the brighter the star, the smaller the magnitude, Bright first magnitude stars are 1st-class stars, the system was a simple delineation of stellar brightness into six distinct groups but made no allowance for the variations in brightness within a group. He concluded that first magnitude stars measured 2 arc minutes in apparent diameter, with second through sixth magnitude stars measuring 1 1⁄2′, 1 1⁄12′, 3⁄4′, 1⁄2′, the development of the telescope showed that these large sizes were illusory—stars appeared much smaller through the telescope. However, early telescopes produced a spurious disk-like image of a star that was larger for brighter stars, early photometric measurements demonstrated that first magnitude stars are about 100 times brighter than sixth magnitude stars. Thus in 1856 Norman Pogson of Oxford proposed that a scale of 5√100 ≈2.512 be adopted between magnitudes, so five magnitude steps corresponded precisely to a factor of 100 in brightness. Every interval of one magnitude equates to a variation in brightness of 5√100 or roughly 2.512 times. Consequently, a first magnitude star is about 2.5 times brighter than a second star,2.52 brighter than a third magnitude star,2.53 brighter than a fourth magnitude star. This is the modern system, which measures the brightness, not the apparent size. Using this logarithmic scale, it is possible for a star to be brighter than “first class”, so Arcturus or Vega are magnitude 0, and Sirius is magnitude −1.46. As mentioned above, the scale appears to work in reverse, the larger the negative value, the brighter
4.
Greek language
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Greek is an independent branch of the Indo-European family of languages, native to Greece and other parts of the Eastern Mediterranean. It has the longest documented history of any living language, spanning 34 centuries of written records and its writing system has been the Greek alphabet for the major part of its history, other systems, such as Linear B and the Cypriot syllabary, were used previously. The alphabet arose from the Phoenician script and was in turn the basis of the Latin, Cyrillic, Armenian, Coptic, Gothic and many other writing systems. Together with the Latin texts and traditions of the Roman world, during antiquity, Greek was a widely spoken lingua franca in the Mediterranean world and many places beyond. It would eventually become the official parlance of the Byzantine Empire, the language is spoken by at least 13.2 million people today in Greece, Cyprus, Italy, Albania, Turkey, and the Greek diaspora. Greek roots are used to coin new words for other languages, Greek. Greek has been spoken in the Balkan peninsula since around the 3rd millennium BC, the earliest written evidence is a Linear B clay tablet found in Messenia that dates to between 1450 and 1350 BC, making Greek the worlds oldest recorded living language. Among the Indo-European languages, its date of earliest written attestation is matched only by the now extinct Anatolian languages, the Greek language is conventionally divided into the following periods, Proto-Greek, the unrecorded but assumed last ancestor of all known varieties of Greek. The unity of Proto-Greek would have ended as Hellenic migrants entered the Greek peninsula sometime in the Neolithic era or the Bronze Age, Mycenaean Greek, the language of the Mycenaean civilisation. It is recorded in the Linear B script on tablets dating from the 15th century BC onwards, Ancient Greek, in its various dialects, the language of the Archaic and Classical periods of the ancient Greek civilisation. It was widely known throughout the Roman Empire, after the Roman conquest of Greece, an unofficial bilingualism of Greek and Latin was established in the city of Rome and Koine Greek became a first or second language in the Roman Empire. The origin of Christianity can also be traced through Koine Greek, Medieval Greek, also known as Byzantine Greek, the continuation of Koine Greek in Byzantine Greece, up to the demise of the Byzantine Empire in the 15th century. Much of the written Greek that was used as the language of the Byzantine Empire was an eclectic middle-ground variety based on the tradition of written Koine. Modern Greek, Stemming from Medieval Greek, Modern Greek usages can be traced in the Byzantine period and it is the language used by the modern Greeks, and, apart from Standard Modern Greek, there are several dialects of it. In the modern era, the Greek language entered a state of diglossia, the historical unity and continuing identity between the various stages of the Greek language is often emphasised. Greek speakers today still tend to regard literary works of ancient Greek as part of their own rather than a foreign language and it is also often stated that the historical changes have been relatively slight compared with some other languages. According to one estimation, Homeric Greek is probably closer to demotic than 12-century Middle English is to modern spoken English, Greek is spoken by about 13 million people, mainly in Greece, Albania and Cyprus, but also worldwide by the large Greek diaspora. Greek is the language of Greece, where it is spoken by almost the entire population
5.
Meteor
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A meteoroid is a small rocky or metallic body in outer space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects, objects smaller than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars and this phenomenon is called a meteor or shooting star. A series of many meteors appearing seconds or minutes apart and appearing to originate from the fixed point in the sky is called a meteor shower. If that object withstands ablation from its passage through the atmosphere as a meteor and impacts with the ground, an estimated 15,000 tonnes of meteoroids, micrometeoroids and different forms of space dust enter Earths atmosphere each year. In 1995, Beech and Steel, writing in the Quarterly Journal of the Royal Astronomical Society, according to Rubin and Grossman, the minimum size of an asteroid is given by what can be discovered from Earth-bound telescopes, so the distinction between meteoroid and asteroid is fuzzy. Some of the smallest asteroids discovered are 2008 TS26 with H =33.2 and 2011 CQ1 with H =32.1 both with a size of 1 meter. Objects smaller than meteoroids are classified as micrometeoroids and cosmic dust, the Minor Planet Center does not use the term meteoroid. Almost all meteoroids contain extraterrestrial nickel and iron and they have three main classifications, iron, stone, and stony-iron. Some stone meteoroids contain grain-like inclusions known as chondrules and are called chondrites, stoney meteoroids without these features are called achondrites, which are typically formed from extraterrestrial igneous activity, they contain little or no extraterrestrial iron. The composition of meteoroids can be inferred as they pass through Earths atmosphere from their trajectories and their effects on radio signals also give information, especially useful for daytime meteors, which are otherwise very difficult to observe. From these trajectory measurements, meteoroids have been found to have many different orbits, some clustering in streams associated with a parent comet. Debris from meteoroid streams may eventually be scattered into other orbits, the study of meteorites also gives insights into the composition of non-ephemeral meteoroids. Most meteoroids come from the belt, having been perturbed by the gravitational influences of planets. Some meteoroids are pieces of planets or moons, such as Mars or our moon, meteoroids travel around the Sun in a variety of orbits and at various velocities. The fastest ones move at about 42 kilometers per second through space in the vicinity of Earths orbit, Earth travels at about 29.6 kilometers per second. Thus, when meteoroids meet Earths atmosphere head-on, the speed may reach about 71 kilometers per second. Meteoroids moving through Earths orbital space average about 20 km/s, on January 17,2013 at 05,21 PST, a 1 meter-sized comet from the Oort cloud entered Earth atmosphere over a wide area in California and Nevada
6.
Full moon
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A full moon is the lunar phase that occurs when the Moon is completely illuminated as seen from Earth. This occurs when Earth is located directly between the Sun and the Moon and this means that the hemisphere of the Moon that is facing Earth is almost fully illuminated by the Sun and appears round. On some occasions at the time of full moon there is also a lunar eclipse so the face appears reddish due to the rayleigh scattering of blue light in Earths atmosphere. Lunar eclipses can occur only at full moon, where the Moons orbit allows it to pass through Earths shadow, Lunar eclipses do not occur every month because the Moon usually passes above or below Earths shadow. Lunar eclipses can only when the full moon occurs near the two nodes of the orbit, either the ascending or descending node. This causes eclipses to occur about every 6 months. The time interval between similar lunar phases—the synodic month—averages about 29.53 days, therefore, in those lunar calendars in which each month begins on the new moon, the full moon falls on either the 14th or 15th of the lunar month. Because calendar months have a number of days, lunar months may be either 29 or 30 days long. A full moon is thought of as an event of a full nights duration. This is somewhat misleading because the Moon seen from Earth is continuously becoming larger and/or smaller and its absolute maximum size occurs at the moment expansion has stopped. For any given location, about half of these absolute maximum full moons will be visible, as the other half occur during the day. Many almanacs list full moons not just by date, but by their time as well. Typical monthly calendars that include phases of the Moon may be offset by one day if intended for use in a different time zone, Full moons are generally a poor time to conduct astronomical observations, because the bright reflected sunlight from the Moon overwhelms the dimmer light from stars. On 12 December 2008, the moon occurred closer to the Earth than it had been at any time for the previous 15 years. On 19 March 2011, another full moon occurred, closer to the Earth than at any time for the previous ~18 years. On 14 November 2016, a full moon occurred closer to the Earth than at any time for the previous 68 years. The true time of a full moon may differ from this approximation by up to about 14.5 hours as a result of the non-circularity of the moons orbit, see New moon for an explanation of the formula and its parameters. The age and apparent size of the full moon vary in a cycle of just under 14 synodic months, Full moons are traditionally associated with temporal insomnia, insanity and various magical phenomena such as lycanthropy
7.
Impact event
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An impact event is a collision between astronomical objects causing measurable effects. Impact events have physical consequences and have found to regularly occur in planetary systems, though the most frequent involve asteroids. Impact craters and structures are dominant landforms on many of the Solar Systems solid objects and present the strongest empirical evidence for their frequency, Impact events appear to have played a significant role in the evolution of the Solar System since its formation. Notable impact events include the Chicxulub impact,66 million years ago, throughout recorded history, hundreds of Earth impacts have been reported, with some occurrences causing deaths, injuries, property damage, or other significant localised consequences. One of the best-known recorded impacts in modern times was the Tunguska event, the Comet Shoemaker–Levy 9 impact provided the first direct observation of an extraterrestrial collision of Solar System objects, when the comet broke apart and collided with Jupiter in July 1994. Impact events have been a plot and background element in science fiction, Impact structures are the result of impact events on solid objects and, as the dominant landforms on many of the Systems solid objects, present the most solid evidence of prehistoric events. Small objects frequently collide with Earth, there is an inverse relationship between the size of the object and the frequency of such events. The lunar cratering record shows that the frequency of impacts decreases as approximately the cube of the craters diameter. Asteroids with a 1 km diameter strike Earth every 500,000 years on average, large collisions – with 5 km objects – happen approximately once every twenty million years. The last known impact of an object of 10 km or more in diameter was at the Cretaceous–Paleogene extinction event 66 million years ago, the energy released by an impactor depends on diameter, density, velocity, and angle. The diameter of most near-Earth asteroids that have not been studied by radar or infrared can generally only be estimated within about a factor of 2 based on the asteroid brightness, the density is generally assumed because the diameter and mass are also generally estimates. The minimum impact velocity on Earth is 11 km/s with asteroid impacts averaging around 17 km/s, the most probable impact angle is 45 degrees. Stony asteroids with a diameter of 4 meters enter Earths atmosphere approximately once per year. Asteroids with a diameter of 7 meters enter the atmosphere about every 5 years with as much energy as the atomic bomb dropped on Hiroshima. These ordinarily explode in the atmosphere and most or all of the solids are vaporized. However, asteroids with a diameter of 20 m, and which strike Earth approximately twice every century, the 2013 Chelyabinsk meteor was estimated to be about 20 m in diameter with an airburst of around 500 kilotons, an explosion 30 times the one over Hiroshima. Much larger objects may impact the solid earth and create a crater, objects with a diameter less than 1 m are called meteoroids and seldom make it to the ground to become meteorites. Although no human is known to have been killed directly by an impact, in 2005 it was estimated that the chance of a single person born today dying due to an impact is around 1 in 200,000
8.
Apparent magnitude
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The apparent magnitude of a celestial object is a number that is a measure of its brightness as seen by an observer on Earth. The brighter an object appears, the lower its magnitude value, the Sun, at apparent magnitude of −27, is the brightest object in the sky. It is adjusted to the value it would have in the absence of the atmosphere, furthermore, the magnitude scale is logarithmic, a difference of one in magnitude corresponds to a change in brightness by a factor of 5√100, or about 2.512. The measurement of apparent magnitudes or brightnesses of celestial objects is known as photometry, apparent magnitudes are used to quantify the brightness of sources at ultraviolet, visible, and infrared wavelengths. An apparent magnitude is measured in a specific passband corresponding to some photometric system such as the UBV system. In standard astronomical notation, an apparent magnitude in the V filter band would be denoted either as mV or often simply as V, the scale used to indicate magnitude originates in the Hellenistic practice of dividing stars visible to the naked eye into six magnitudes. The brightest stars in the sky were said to be of first magnitude, whereas the faintest were of sixth magnitude. Each grade of magnitude was considered twice the brightness of the following grade and this rather crude scale for the brightness of stars was popularized by Ptolemy in his Almagest, and is generally believed to have originated with Hipparchus. This implies that a star of magnitude m is 2.512 times as bright as a star of magnitude m +1 and this figure, the fifth root of 100, became known as Pogsons Ratio. The zero point of Pogsons scale was defined by assigning Polaris a magnitude of exactly 2. However, with the advent of infrared astronomy it was revealed that Vegas radiation includes an Infrared excess presumably due to a disk consisting of dust at warm temperatures. At shorter wavelengths, there is negligible emission from dust at these temperatures, however, in order to properly extend the magnitude scale further into the infrared, this peculiarity of Vega should not affect the definition of the magnitude scale. Therefore, the scale was extrapolated to all wavelengths on the basis of the black body radiation curve for an ideal stellar surface at 11000 K uncontaminated by circumstellar radiation. On this basis the spectral irradiance for the zero magnitude point, with the modern magnitude systems, brightness over a very wide range is specified according to the logarithmic definition detailed below, using this zero reference. In practice such apparent magnitudes do not exceed 30, astronomers have developed other photometric zeropoint systems as alternatives to the Vega system. The AB magnitude zeropoint is defined such that an objects AB, the dimmer an object appears, the higher the numerical value given to its apparent magnitude, with a difference of 5 magnitudes corresponding to a brightness factor of exactly 100. Since an increase of 5 magnitudes corresponds to a decrease in brightness by a factor of exactly 100, each magnitude increase implies a decrease in brightness by the factor 5√100 ≈2.512. Inverting the above formula, a magnitude difference m1 − m2 = Δm implies a brightness factor of F2 F1 =100 Δ m 5 =100.4 Δ m ≈2.512 Δ m
9.
Impact crater
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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, Impact craters are the dominant geographic features on many solid Solar System objects including the Moon, Mercury, Callisto, Ganymede and most small moons and asteroids. Where such processes have destroyed most of the original crater topography and this indicates that there should be far more relatively young craters on the planet than have been discovered so far. Note that the rate of impact cratering in the outer Solar System could be different from the inner Solar System, although Earths active surface processes quickly destroy the impact record, about 190 terrestrial impact craters have been identified. They are also found in the stable interior regions of continents. Impact craters are not to be confused with landforms that may appear similar, including calderas, sinkholes, glacial cirques, ring dikes, salt domes, and others. Daniel Barringer was one of the first to identify an impact crater, Meteor Crater in Arizona, in the 1920s, the American geologist Walter H. Bucher studied a number of sites now recognized as impact craters in the United States. He concluded they had created by some great explosive event. However, in 1936, the geologists John D, albritton Jr. revisited Buchers studies and concluded that the craters that he studied were probably formed by impacts. The concept of impact cratering remained more or less speculative until the 1960s, armed with the knowledge of shock-metamorphic features, Carlyle S. By 1970, they had identified more than 50. Although their work was controversial, the American Apollo Moon landings, because the processes of erosion on the Moon are minimal, craters persist almost indefinitely. Since the Earth could be expected to have roughly the same cratering rate as the Moon, Impact cratering involves high velocity collisions between solid objects, typically much greater than the velocity of sound in those objects. Such hyper-velocity impacts produce physical effects such as melting and vaporization that do not occur in familiar sub-sonic collisions. On Earth, ignoring the effects of travel through the atmosphere. The fastest impacts occur at about 72 km/s in the worst case scenario in which an object in a retrograde near-parabolic orbit hits Earth, the median impact velocity on Earth is about 20 km/s. The larger the meteoroid the more of its initial cosmic velocity it preserves, while an object of 9,000 kg maintains about 6% of its original velocity, one of 900,000 kg already preserves about 70%. Extremely large bodies are not slowed by the atmosphere at all, impacts at these high speeds produce shock waves in solid materials, and both impactor and the material impacted are rapidly compressed to high density
10.
Asteroid
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Asteroids are minor planets, especially those of the inner Solar System. The larger ones have also been called planetoids and these terms have historically been applied to any astronomical object orbiting the Sun that did not show the disc of a planet and was not observed to have the characteristics of an active comet. As minor planets in the outer Solar System were discovered and found to have volatile-based surfaces that resemble those of comets, in this article, the term asteroid refers to the minor planets of the inner Solar System including those co-orbital with Jupiter. There are millions of asteroids, many thought to be the remnants of planetesimals. The large majority of known asteroids orbit in the belt between the orbits of Mars and Jupiter, or are co-orbital with Jupiter. However, other orbital families exist with significant populations, including the near-Earth objects, individual asteroids are classified by their characteristic spectra, with the majority falling into three main groups, C-type, M-type, and S-type. These were named after and are identified with carbon-rich, metallic. The size of asteroids varies greatly, some reaching as much as 1000 km across, asteroids are differentiated from comets and meteoroids. In the case of comets, the difference is one of composition, while asteroids are composed of mineral and rock, comets are composed of dust. In addition, asteroids formed closer to the sun, preventing the development of the aforementioned cometary ice, the difference between asteroids and meteoroids is mainly one of size, meteoroids have a diameter of less than one meter, whereas asteroids have a diameter of greater than one meter. Finally, meteoroids can be composed of either cometary or asteroidal materials, only one asteroid,4 Vesta, which has a relatively reflective surface, is normally visible to the naked eye, and this only in very dark skies when it is favorably positioned. Rarely, small asteroids passing close to Earth may be visible to the eye for a short time. As of March 2016, the Minor Planet Center had data on more than 1.3 million objects in the inner and outer Solar System, the United Nations declared June 30 as International Asteroid Day to educate the public about asteroids. The date of International Asteroid Day commemorates the anniversary of the Tunguska asteroid impact over Siberia, the first asteroid to be discovered, Ceres, was found in 1801 by Giuseppe Piazzi, and was originally considered to be a new planet. In the early half of the nineteenth century, the terms asteroid. Asteroid discovery methods have improved over the past two centuries. This task required that hand-drawn sky charts be prepared for all stars in the band down to an agreed-upon limit of faintness. On subsequent nights, the sky would be charted again and any moving object would, hopefully, the expected motion of the missing planet was about 30 seconds of arc per hour, readily discernible by observers
11.
Comet
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Community of Metros is a system of international railway benchmarking. CoMET consists of metro systems from around the world. Each metro has a volume of at least 500 million passengers annually, the four main objectives of CoMET are, To build measures to establish metro best practice. To provide comparative information both for the board and the government. To introduce a system of measures for management and these objectives were discussed in detail at the CoMET Annual Meeting 2016, hosted by SMRT Trains of SMRT Corporation. The meeting was held at Singapore in November 2016, in the UITP conference of 1982, London Underground and Hamburger Hochbahn decided to create a benchmarking exercise to compare their two railways with additional data for other 24 metro systems. The project was successful despite the fact that metros were very different in sizes, structures, however, CoMET used the Key Performance Indicator innovatively to solve the problem. In 1994, the Mass Transit Railway of Hong Kong proposed to London Underground, Berlin U-Bahn, New York City Subway, thus, the metros can exchange performance data and investigate best practice amongst similar heavy metros. These five metros are later known as the Group of Five, over time, other large transit systems joined the group. For example, Mexico City Metro, São Paulo Metro and Tokyo Metro joined in 1996, with eight members in total, the group became known as the Community of Metros. Following the success of the CoMET, the Nova group was created in 1998 as another benchmarking association, the Nova is currently consisted of 14 metro systems from around the world. Later, Moscow Metro joined the CoMET in 1999, madrid Metro transferred from Nova to CoMET in 2004. Santiago Metro and Beijing Subway joined in 2008, taipei Metro was the last member to join the CoMET which also joined in 2010
12.
Sutter's Mill meteorite
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The Sutters Mill meteorite is a carbonaceous chondrite which entered the Earths atmosphere and broke up at about 07,51 Pacific time on April 22,2012. The name comes from the Sutters Mill, the California Gold Rush site and this was the largest meteoroid impact over land since asteroid 2008 TC3. As of May 2014,79 fragments have been documented with a find location. The largest weighs 205 grams, and the second largest weighs 42 grams, the meteorite was found to contain some of the oldest material in the solar system. Two 10-micron diamond grains were found in the meteorite recovered before the rain fell, in primitive meteorites like Sutters Mill, some grains survived from what existed in the cloud of gas, dust and ice that formed the solar system. During the 2012 Lyrids meteor shower, a bolide and sonic boom rattled buildings in California, the bolide air burst was caused by a random meteoroid, not a member of the Lyrids shower. The bolide was so bright that witnesses were seeing spots afterward, the falling meteorites were detected by weather radar over an area centered on the Sutters Mill site in Coloma, between Auburn, California, and Placerville, California. Robert Ward found a small CM chondrite fragment in the Henningsen Lotus Park just west of Coloma, later that day, Peter Jenniskens found a crushed 4 g meteorite in the parking lot of that same park and Brien Cook found a 5 g meteorite off Petersen Road in Lotus. These were the only meteorites found before rain hit the area on 25 April, on 1 May 2012, the James W. Marshall Gold Discovery State Historic Parks Ranger Suzie Matin discovered two pieces of the meteorite in her front yard. The park contains what is now known as Sutters Mill, ground-based searches resulted in the additional recovery of two pristinely collected meteorites for scientific study. A consortium of over 50 scientists investigated the circumstances of the impact, the event was recorded by two infrasound monitoring stations of the Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System. The preliminary analysis are indicative of energy yield of approximately 4 kilotons of TNT equivalent, hiroshimas Little Boy had a yield of about 16 kt. The air burst had approximate coordinates of 37. 6°N120. 5°W /37.6, before entry in Earths atmosphere, the meteoroid probably had an absolute magnitude of roughly 31. The meteoroid entered at a speed of 28.6 ±0.7 km/s. It broke apart at an altitude of 48 km, the highest breakup event on record resulting in meteorites on the ground, before entry, the meteoroid moved on an eccentric orbit, stretching from just inside the orbit of Jupiter to the orbit of Mercury. The orbit had an inclination and an orbital period suggesting that this meteoroid originated in the 3,1 mean motion resonance with Jupiter. The CM chondrite Maribo moved on an orbit, but rotated by 120 degrees in the direction of the line of apsides. The meteorite type is similar to that of the 1969 Murchison meteorite in Australia, the Sutters Mill meteorite originated from near the surface of its parent body
13.
Chelyabinsk meteor
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It quickly became a brilliant superbolide meteor over the southern Ural region. The light from the meteor was brighter than the Sun, visible up to 100 km away and it was observed over a wide area of the region and in neighbouring republics. Some eyewitnesses also felt intense heat from the fireball, on account of its high velocity and shallow angle of atmospheric entry, the object exploded in an air burst over Chelyabinsk Oblast, at a height of around 29.7 km. The explosion generated a bright flash, producing a hot cloud of dust and gas that penetrated to 26.2 km, the object was undetected before its atmospheric entry, in part because its radiant was close to the Sun. Its explosion created panic among residents, and about 1,500 people were injured seriously enough to seek medical treatment. Some 7,200 buildings in six cities across the region were damaged by the shock wave. The Chelyabinsk meteor is also the only confirmed to have resulted in a large number of injuries. Amateur videos showed a fireball streaking across the sky and a loud boom several minutes afterwards, some eyewitnesses also felt intense heat from the fireball. The event began at 09,20,21 Yekaterinburg time, several minutes after sunrise in Chelyabinsk, according to eyewitnesses, the bolide appeared brighter than the sun, as was later confirmed by NASA. An image of the object was taken shortly after it entered the atmosphere by the weather satellite Meteosat 9. Witnesses in Chelyabinsk said that the air of the city smelled like gunpowder, sulfur and burning odors starting about 1 hour after the fireball, the visible phenomenon due to the passage of an asteroid or meteoroid through the atmosphere is called a meteor. If the object reaches the ground, then it is called a meteorite, during the Chelyabinsk meteoroids traversal, there was a bright object trailing smoke, then an air burst that caused a powerful blast wave. The latter was the cause of the damage to thousands of buildings in Chelyabinsk. The fragments then entered dark flight and created a field of numerous meteorites on the snow-covered ground. The last time a similar phenomenon was observed in the Chelyabinsk region was the Kunashak meteor shower of 1949, preliminary estimates released by the Russian Federal Space Agency indicated the object was an asteroid moving at about 30 km/s in a low trajectory when it entered Earths atmosphere. According to the Russian Academy of Sciences, the meteor then pushed through the atmosphere at a velocity of 15 km/s, the radiant appears from video recordings to have been above and to the left of the rising Sun. On 1 March 2013 NASA published a synopsis of the event, stating that at peak brightness. The air bursts blast wave, when it hit the ground, the Russian Geographical Society said the passing of the meteor over Chelyabinsk caused three blasts of different energy
14.
Meteoroid
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A meteoroid is a small rocky or metallic body in outer space. Meteoroids are significantly smaller than asteroids, and range in size from small grains to 1 meter-wide objects, objects smaller than this are classified as micrometeoroids or space dust. Most are fragments from comets or asteroids, whereas others are collision impact debris ejected from bodies such as the Moon or Mars and this phenomenon is called a meteor or shooting star. A series of many meteors appearing seconds or minutes apart and appearing to originate from the fixed point in the sky is called a meteor shower. If that object withstands ablation from its passage through the atmosphere as a meteor and impacts with the ground, an estimated 15,000 tonnes of meteoroids, micrometeoroids and different forms of space dust enter Earths atmosphere each year. In 1995, Beech and Steel, writing in the Quarterly Journal of the Royal Astronomical Society, according to Rubin and Grossman, the minimum size of an asteroid is given by what can be discovered from Earth-bound telescopes, so the distinction between meteoroid and asteroid is fuzzy. Some of the smallest asteroids discovered are 2008 TS26 with H =33.2 and 2011 CQ1 with H =32.1 both with a size of 1 meter. Objects smaller than meteoroids are classified as micrometeoroids and cosmic dust, the Minor Planet Center does not use the term meteoroid. Almost all meteoroids contain extraterrestrial nickel and iron and they have three main classifications, iron, stone, and stony-iron. Some stone meteoroids contain grain-like inclusions known as chondrules and are called chondrites, stoney meteoroids without these features are called achondrites, which are typically formed from extraterrestrial igneous activity, they contain little or no extraterrestrial iron. The composition of meteoroids can be inferred as they pass through Earths atmosphere from their trajectories and their effects on radio signals also give information, especially useful for daytime meteors, which are otherwise very difficult to observe. From these trajectory measurements, meteoroids have been found to have many different orbits, some clustering in streams associated with a parent comet. Debris from meteoroid streams may eventually be scattered into other orbits, the study of meteorites also gives insights into the composition of non-ephemeral meteoroids. Most meteoroids come from the belt, having been perturbed by the gravitational influences of planets. Some meteoroids are pieces of planets or moons, such as Mars or our moon, meteoroids travel around the Sun in a variety of orbits and at various velocities. The fastest ones move at about 42 kilometers per second through space in the vicinity of Earths orbit, Earth travels at about 29.6 kilometers per second. Thus, when meteoroids meet Earths atmosphere head-on, the speed may reach about 71 kilometers per second. Meteoroids moving through Earths orbital space average about 20 km/s, on January 17,2013 at 05,21 PST, a 1 meter-sized comet from the Oort cloud entered Earth atmosphere over a wide area in California and Nevada
15.
Atmospheric entry
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Atmospheric entry is the movement of an object from outer space into and through the gases of an atmosphere of a planet, dwarf planet or natural satellite. Technologies and procedures allowing the atmospheric entry, descent and landing of spacecraft are collectively abbreviated as EDL. Atmospheric drag and aerodynamic heating can cause atmospheric breakup capable of completely disintegrating smaller objects and these forces may cause objects with lower compressive strength to explode. Manned space vehicles must be slowed to subsonic speeds before parachutes or air brakes may be deployed, such vehicles have kinetic energies typically between 50 and 1800 MJoules, and atmospheric dissipation is the only way of expending the kinetic energy. While the high temperature generated at the surface of the shield is due to adiabatic compression. Other smaller energy losses include black body radiation directly from the hot gasses, ballistic warheads and expendable vehicles do not require slowing at re-entry, and in fact, are made streamlined so as to maintain their speed. Uncontrolled, objects accelerate through the atmosphere at extreme velocities under the influence of Earths gravity, most controlled objects enter at hypersonic speeds due to their suborbital, orbital, or unbounded trajectories. Various advanced technologies have developed to enable atmospheric reentry and flight at extreme velocities. Practical development of systems began as the range and reentry velocity of ballistic missiles increased. For early short-range missiles, like the V-2, stabilization and aerodynamic stress were important issues, medium-range missiles like the Soviet R-5, with a 1200 km range, required ceramic composite heat shielding on separable reentry vehicles. The first ICBMs, with ranges of 8000 to 12,000 km, were possible with the development of modern ablative heat shields. In the U. S. this technology was pioneered by H. Julian Allen at Ames Research Center, over the decades since the 1950s, a rich technical jargon has grown around the engineering of vehicles designed to enter planetary atmospheres. It is recommended that the review the jargon glossary before continuing with this article on atmospheric reentry. When atmospheric entry is part of a landing or recovery, particularly on a planetary body other than Earth, entry is part of a phase referred to as entry, descent and landing. When the atmospheric entry returns to the body that the vehicle had launched from. These four shadowgraph images represent early reentry-vehicle concepts, if the reentry vehicle is made blunt, air cannot get out of the way quickly enough, and acts as an air cushion to push the shock wave and heated shock layer forward. Since most of the hot gases are no longer in contact with the vehicle. The Allen and Eggers discovery, though initially treated as a secret, was eventually published in 1958
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Air-burst
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Air burst artillery has a long history. The shrapnel shell was invented by Henry Shrapnel of the British army in about 1780 to increase the effectiveness of canister shot and it was widely used by the time of the War of 1812 and stayed in use until it was superseded during the First World War. Modern shells, though sometimes called shrapnel shells, actually produce fragments and splinters, when infantry moved into deep trenches, shrapnel shells were rendered useless and high-explosive shells were used to attack field fortifications and troops in the open. The time fuses for the shells could be set to function on contact or in the air, during World War II a proximity fuze was developed, which was controlled by a doppler radar device within the shell that caused it to explode when near the target. During the Vietnam War, air bursting shells were used to effect to defend US Army bases. This tactic was known as Killer Junior when referring to 105 mm or 155 mm shells, another recent development is computer programmable rounds. Weapons using this new technology include the XM29, XM25, XM307, K11 and this mach stem only occurs near ground level, and is similar in shape to the letter Y when viewed from the side. Airbursting also minimizes fallout by keeping the fireball from touching the ground, limiting the amount of debris that is vaporized, in nuclear warfare, air bursts are used against soft targets such as cities in countervalue targeting, or airfields, radar systems and mobile ICBMs in counterforce targeting. List of meteor air bursts Laydown delivery Toss bombing Munition fuzes
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International Astronomical Union
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The International Astronomical Union is an international association of professional astronomers, at the PhD level and beyond, active in professional research and education in astronomy. Among other activities, it acts as the recognized authority for assigning designations to celestial bodies. The IAU is a member of the International Council for Science and its main objective is to promote and safeguard the science of astronomy in all its aspects through international cooperation. The IAU maintains friendly relations with organizations that include amateur astronomers in their membership, the IAU has its head office on the second floor of the Institut dAstrophysique de Paris in the 14th arrondissement of Paris. The IAU is also responsible for the system of astronomical telegrams which are produced and distributed on its behalf by the Central Bureau for Astronomical Telegrams, the Minor Planet Center also operates under the IAU, and is a clearinghouse for all non-planetary or non-moon bodies in the Solar System. The Working Group for Meteor Shower Nomenclature and the Meteor Data Center coordinate the nomenclature of meteor showers, the IAU was founded on July 28,1919, at the Constitutive Assembly of the International Research Council held in Brussels, Belgium. The 7 initial member states were Belgium, Canada, France, Great Britain, Greece, Japan, the first executive committee consisted of Benjamin Baillaud, Alfred Fowler, and four vice presidents, William Campbell, Frank Dyson, Georges Lecointe, and Annibale Riccò. Thirty-two Commissions were appointed at the Brussels meeting and focused on topics ranging from relativity to minor planets, the reports of these 32 Commissions formed the main substance of the first General Assembly, which took place in Rome, Italy, May 2–10,1922. By the end of the first General Assembly, ten nations had joined the Union. Although the Union was officially formed eight months after the end of World War I, the first 50 years of the Unions history are well documented. Subsequent history is recorded in the form of reminiscences of past IAU Presidents, twelve of the fourteen past General Secretaries in the period 1964-2006 contributed their recollections of the Unions history in IAU Information Bulletin No.100. Six past IAU Presidents in the period 1976–2003 also contributed their recollections in IAU Information Bulletin No.104, the IAU includes a total of 12,664 individual members who are professional astronomers from 96 countries worldwide. 83% of all members are male, while 17% are female, among them the unions current president. Membership also includes 79 national members, professional astronomical communities representing their countrys affiliation with the IAU, the sovereign body of the IAU is its General Assembly, which comprises all members. The Assembly determines IAU policy, approves the Statutes and By-Laws of the Union, the right to vote on matters brought before the Assembly varies according to the type of business under discussion. On budget matters, votes are weighted according to the subscription levels of the national members. A second category vote requires a turnout of at least two-thirds of national members in order to be valid, an absolute majority is sufficient for approval in any vote, except for Statute revision which requires a two-thirds majority. An equality of votes is resolved by the vote of the President of the Union, since 1922, the IAU General Assembly meets every three years, with the exception of the period between 1938 and 1948, due to World War II
18.
List of meteor air bursts
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Many explosions have been recorded in Earths atmosphere that are likely caused by the air burst that results from a meteor burning up as it hits the atmosphere. These types of meteors are known as fireballs with the brightest known as superbolides. Contrary to smaller and common shooting stars, these larger meteors were originally asteroids, the best known is the 1908 Tunguska event. The appearance of extremely bright fireballs traveling across the sky is often witnessed from a distance, such as the 1947 Sikhote-Alin meteor, if the bolide is large enough, fragments may survive such as the Chelyabinsk meteorite. Modern developments in infrasound detection by the Comprehensive Nuclear-Test-Ban Treaty Organization, the table from Earth Impact Effects Program estimates the average frequency of airbursts and their energy yield in kilotons or megatons of TNT equivalent. While airbursts undoubtedly happened prior to the 20th century, reliable reports of such are quite scanty, a relatively well-documented case is the 1490 Ching-yang event which has an unknown energy yield but was apparently powerful enough to cause 10,000 deaths. Modern researchers are skeptical about the figure, but the Tunguska event could have destroyed a highly populous district. Depending on the estimate, there were only 3-4 known airbursts in the 20th century with yield greater than 100 kilotons. Most values for the 1930 Curuçá River event put it below 1 megaton, the first airburst of the 21st century with yield greater than 100 kilotons came from the 2013 Chelyabinsk meteor, which had an estimated diameter of 20 meters. The Comprehensive Nuclear-Test-Ban Treaty Organization and modern technology has improved multiple detection of airbursts with energy yield 1-2 kilotons every year within the last decade. Borovička, J. Brachet, N. Brown, D. Campbell-Brown, M. Ceranna, L. Cooke, W. de Groot-Hedlin, C. Drob, D. P. Edwards, W. Evers, L. G. Garces, M. Gill, J. Hedlin, M. Kingery, A. Laske, G. Le Pichon, A. Mialle, P. Moser, D. E. Saffer, A. Silber, E. Smets, P. Spalding, R. E. Spurný, P. Tagliaferri, a 500-kiloton airburst over Chelyabinsk and an enhanced hazard from small impactors. PMID24196713. de la Fuente Marcos, C. de la Fuente Marcos, recent multi-kiloton impact events, are they truly random. Monthly Notices of the Royal Astronomical Society, Letters, yau, Kevin, Weissman, Paul, Yeomans, Donald. Meteorite falls in China and some related human casualty events
19.
Tunguska event
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The Tunguska event was a large explosion that occurred near the Stony Tunguska River, in Yeniseysk Governorate, Russia, on the morning of 30 June 1908. The explosion over the sparsely populated Eastern Siberian Taiga flattened 2,000 km2 of forest yet caused no known human casualties, the explosion is generally attributed to the air burst of a meteoroid. The Tunguska event is the largest impact event on Earth in recorded history, studies have yielded different estimates of the meteoroids size, on the order of 60 to 190 metres, depending on whether the body was a comet or a denser asteroid. Since the 1908 event, there have been an estimated 1,000 scholarly papers published on the Tunguska explosion. In 2013, a team of researchers published results of micro-samples from a peat bog near the center of the affected area showing fragments that may be of meteoritic origin. An explosion of this magnitude would be capable of destroying a large metropolitan area and this event has helped to spark discussion of asteroid impact avoidance. About ten minutes later, there was a flash and a similar to artillery fire. Eyewitnesses closer to the explosion reported that the source of the sound moved from the east to the north of them, the sounds were accompanied by a shock wave that knocked people off their feet and broke windows hundreds of kilometres away. The majority of witnesses reported only the sounds and tremors, eyewitness accounts vary regarding the sequence and duration of the events. The explosion registered at seismic stations across Eurasia and it is estimated that, in some places, the resulting shock wave was equivalent to an earthquake measuring 5.0 on the Richter magnitude scale. It also produced fluctuations in atmospheric pressure strong enough to be detected in Great Britain, testimony of S. Semenov, as recorded by Leonid Kuliks expedition in 1930, At breakfast time I was sitting by the house at Vanavara Trading Post, facing north. I suddenly saw that directly to the north, over Onkouls Tunguska Road, the split in the sky grew larger, and the entire northern side was covered with fire. At that moment I became so hot that I couldnt bear it, as if my shirt was on fire, from the northern side, where the fire was, came strong heat. I wanted to tear off my shirt and throw it down, but then the sky shut closed, and a strong thump sounded, I lost my senses for a moment, but then my wife ran out and led me to the house. After that such noise came, as if rocks were falling or cannons were firing, the earth shook, and when I was on the ground, I pressed my head down, fearing rocks would smash it. When the sky opened up, hot wind raced between the houses, like from cannons, which left traces in the ground like pathways, later we saw that many windows were shattered, and in the barn a part of the iron lock snapped. Testimony of Chuchan of Shanyagir tribe, as recorded by I. M. Suslov in 1926, suddenly we both woke up at the same time. We heard whistling and felt strong wind, Chekaren said, Can you hear all those birds flying overhead
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2009 Sulawesi superbolide
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The 2009 Sulawesi superbolide was an atmospheric fireball blast over Indonesia on October 8,2009, at approximately 03,00 UTC, near the coastal city of Bone in South Sulawesi, island of Sulawesi. The meteoritic impactor broke up at an height of 15–20 km. The impact energy is estimated in the 10 to 50 kiloton TNT equivalent range with the end of this range being more likely. Likely size of impactor was 5–10 m diameter, archived from the original on October 31,2010
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Geologist
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A geologist is a scientist who studies the solid and liquid matter that constitutes the Earth as well as the processes that shape it. Geologists usually study geology, although backgrounds in physics, chemistry, biology, field work is an important component of geology, although many subdisciplines incorporate laboratory work. Some geologists work in the mining business searching for metals, oils and they are also in the forefront of natural hazards and disasters prevention and mitigation, studying natural hazards such as earthquakes, volcanic activity, tsunamis, weather storms. Their studies are used to warn the public of the occurrence of these events. Geologists are also important contributors to climate change discussions, james Hutton is often viewed as the first modern geologist. In 1785 he presented a paper entitled Theory of the Earth to the Royal Society of Edinburgh, Hutton published a two-volume version of his ideas in 1795. The first geological map of the U. S. was produced in 1809 by William Maclure, in 1807, Maclure commenced the self-imposed task of making a geological survey of the United States. Almost every state in the Union was traversed and mapped by him and this antedates William Smiths geological map of England by six years, although it was constructed using a different classification of rocks. Sir Charles Lyell first published his famous book, Principles of Geology and this book, which influenced the thought of Charles Darwin, successfully promoted the doctrine of uniformitarianism. This theory states that slow geological processes have occurred throughout the Earths history and are still occurring today, in contrast, catastrophism is the theory that Earths features formed in single, catastrophic events and remained unchanged thereafter. Though Hutton believed in uniformitarianism, the idea was not widely accepted at the time, most geologists also need skills in GIS and other mapping techniques. Geology students often spend portions of the year, especially the summer though sometimes during a January term, geologists may concentrate their studies or research in one or more of the following disciplines, Dendrochronology, the study of dating based on tree ring patterns. Economic geology, the study of ore genesis, and the mechanisms of ore creation, geochemistry, the applied branch deals with the study of the chemical makeup and behaviour of rocks, and the study of the behaviour of their minerals. Geochronology, the study of isotope geology specifically toward determining the date within the past of rock formation, metamorphism, mineralization and geological events. Geomorphology, the study of landforms and the processes that create them Hydrogeology, igneous petrology, the study of igneous processes such as igneous differentiation, fractional crystallization, intrusive and volcanological phenomena. Isotope geology, the case of the composition of rocks to determine the processes of rock. Metamorphic petrology, the study of the effects of metamorphism on minerals, marine geology, the study of the seafloor, involves geophysical, geochemical, sedimentological and paleontological investigations of the ocean floor and coastal margins. Marine geology has strong ties to physical oceanography and plate tectonics, palaeoclimatology, the application of geological science to determine the climatic conditions present in the Earths atmosphere within the Earths history
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Astronomer
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An astronomer is a scientist in the field of astronomy who concentrates their studies on a specific question or field outside of the scope of Earth. They look at stars, planets, moons, comets and galaxies, as well as other celestial objects — either in observational astronomy. Examples of topics or fields astronomers work on include, planetary science, solar astronomy, there are also related but distinct subjects like physical cosmology which studies the Universe as a whole. Astronomers usually fit into two types, Observational astronomers make direct observations of planets, stars and galaxies, and analyze the data, theoretical astronomers create and investigate models of things that cannot be observed. They use this data to create models or simulations to theorize how different celestial bodies work, there are further subcategories inside these two main branches of astronomy such as planetary astronomy, galactic astronomy or physical cosmology. Today, that distinction has disappeared and the terms astronomer. Professional astronomers are highly educated individuals who typically have a Ph. D. in physics or astronomy and are employed by research institutions or universities. They spend the majority of their time working on research, although quite often have other duties such as teaching, building instruments. The number of astronomers in the United States is actually quite small. The American Astronomical Society, which is the organization of professional astronomers in North America, has approximately 7,000 members. This number includes scientists from other such as physics, geology. The International Astronomical Union comprises almost 10,145 members from 70 different countries who are involved in research at the Ph. D. level. Before CCDs, photographic plates were a method of observation. Modern astronomers spend relatively little time at telescopes usually just a few weeks per year, analysis of observed phenomena, along with making predictions as to the causes of what they observe, takes the majority of observational astronomers time. Astronomers who serve as faculty spend much of their time teaching undergraduate and graduate classes, most universities also have outreach programs including public telescope time and sometimes planetariums as a public service to encourage interest in the field. Those who become astronomers usually have a background in maths, sciences. Taking courses that teach how to research, write and present papers are also invaluable, in college/university most astronomers get a Ph. D. in astronomy or physics. Keeping in mind how few there are it is understood that graduate schools in this field are very competitive
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Geology
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Geology is an earth science concerned with the solid Earth, the rocks of which it is composed, and the processes by which they change over time. Geology can also refer generally to the study of the features of any terrestrial planet. Geology gives insight into the history of the Earth by providing the evidence for plate tectonics, the evolutionary history of life. Geology also plays a role in engineering and is a major academic discipline. The majority of data comes from research on solid Earth materials. These typically fall into one of two categories, rock and unconsolidated material, the majority of research in geology is associated with the study of rock, as rock provides the primary record of the majority of the geologic history of the Earth. There are three types of rock, igneous, sedimentary, and metamorphic. The rock cycle is an important concept in geology which illustrates the relationships between three types of rock, and magma. When a rock crystallizes from melt, it is an igneous rock, the sedimentary rock can then be subsequently turned into a metamorphic rock due to heat and pressure and is then weathered, eroded, deposited, and lithified, ultimately becoming a sedimentary rock. Sedimentary rock may also be re-eroded and redeposited, and metamorphic rock may also undergo additional metamorphism, all three types of rocks may be re-melted, when this happens, a new magma is formed, from which an igneous rock may once again crystallize. Geologists also study unlithified material which typically comes from more recent deposits and these materials are superficial deposits which lie above the bedrock. Because of this, the study of material is often known as Quaternary geology. This includes the study of sediment and soils, including studies in geomorphology, sedimentology and this theory is supported by several types of observations, including seafloor spreading, and the global distribution of mountain terrain and seismicity. This coupling between rigid plates moving on the surface of the Earth and the mantle is called plate tectonics. The development of plate tectonics provided a basis for many observations of the solid Earth. Long linear regions of geologic features could be explained as plate boundaries, mid-ocean ridges, high regions on the seafloor where hydrothermal vents and volcanoes exist, were explained as divergent boundaries, where two plates move apart. Arcs of volcanoes and earthquakes were explained as convergent boundaries, where one plate subducts under another, transform boundaries, such as the San Andreas Fault system, resulted in widespread powerful earthquakes. Plate tectonics also provided a mechanism for Alfred Wegeners theory of continental drift and they also provided a driving force for crustal deformation, and a new setting for the observations of structural geology
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Woods Hole, Massachusetts
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Woods Hole is a census-designated place in the town of Falmouth in Barnstable County, Massachusetts, United States. It lies at the extreme southwest corner of Cape Cod, near Marthas Vineyard, the population was 781 at the 2010 census. Historically, Woods Hole included one of the few good harbors on the side of Cape Cod. The community became a center for whaling, shipping, and fishing, prior to its dominance today by tourism, other notable businessmen established homes on Gansett Point, Nobska Point, and at Quissett Harbor, further from the village center. Woods Hole is located at the southwest tip of the town of Falmouth at 41°31′36″N 70°39′47″W, the term Woods Hole refers to a passage for ships between Vineyard Sound and Buzzards Bay known for its extremely strong current, approaching four knots. The strait separates Cape Cod from the Elizabeth Islands and it is one of four straits allowing maritime passage between Buzzards Bay and the Vineyard Sound. The others are Canapitsit Channel, Quicks Hole and Robinsons Hole, ferries operated by the Steamship Authority run regularly between Woods Hole and Marthas Vineyard. In the past ferries also ran between Woods Hole and Nantucket, but these have been discontinued in recent decades, much of Woods Hole centers around the enclosed harbor of Eel Pond. A drawbridge at the mouth of the harbor allows boats to enter, the local lighthouse at Nobska Point is operated by the United States Coast Guard, and the accompanying house is the home of the commander of the Coast Guard base at Little Harbor. Local landmark The Knob is a rocky outcropping that overlooks Buzzards Bay and it is a part of the privately owned Salt Pond bird sanctuaries. According to the United States Census Bureau, the Woods Hole CDP has an area of 3.9 square miles. 2.1 square miles of it is land, and 1.8 square miles of it is water, the annual Falmouth Road Race brings thousands of runners to Woods Hole in August each year. The Woods Hole School is the home of the Childrens School of Science, founded in 1913, this institution provides science classes for students between 8 and 15 years old that focus on scientific investigation by observation. Students regularly visit ecosystems around the village to study the organisms in their natural environments, the Childrens School of Science draws upon the talent brought to the village by the research institutions but also educates the children of both scientists and locals. Some mention of the Woods Hole Oceanographic Institution is made in the 1975 blockbuster film Jaws as having been the center of research for the fictional character Matt Hooper, Hooper is described as a marine biologist, focusing on the study of sharks. Coincidentally, a white shark was spotted some years later near Woods Hole in September 2004. Woods Hole is part of the Falmouth public school district, served by Mullen-Hall Elementary, Morse Pond Middle School, Lawrence Junior High School, Woods Hole students also often attend Upper Cape Cod Regional Technical High School, Sturgis Charter Public School, and Falmouth Academy. As of the census of 2000, there were 925 people,459 households, there were 942 housing units at an average density of 168. 4/km²
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United States Geological Survey
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The United States Geological Survey is a scientific agency of the United States government. The scientists of the USGS study the landscape of the United States, its resources. The organization has four science disciplines, concerning biology, geography, geology. The USGS is a research organization with no regulatory responsibility. The USGS is a bureau of the United States Department of the Interior, the USGS employs approximately 8,670 people and is headquartered in Reston, Virginia. The USGS also has major offices near Lakewood, Colorado, at the Denver Federal Center, the current motto of the USGS, in use since August 1997, is science for a changing world. The agencys previous slogan, adopted on the occasion of its anniversary, was Earth Science in the Public Service. Prompted by a report from the National Academy of Sciences, the USGS was created, by a last-minute amendment and it was charged with the classification of the public lands, and examination of the geological structure, mineral resources, and products of the national domain. This task was driven by the need to inventory the vast lands added to the United States by the Louisiana Purchase in 1803, the legislation also provided that the Hayden, Powell, and Wheeler surveys be discontinued as of June 30,1879. Clarence King, the first director of USGS, assembled the new organization from disparate regional survey agencies, after a short tenure, King was succeeded in the directors chair by John Wesley Powell. Administratively, it is divided into a Headquarters unit and six Regional Units, Other specific programs include, Earthquake Hazards Program monitors earthquake activity worldwide. The National Earthquake Information Center in Golden, Colorado on the campus of the Colorado School of Mines detects the location, the USGS also runs or supports several regional monitoring networks in the United States under the umbrella of the Advanced National Seismic System. The USGS informs authorities, emergency responders, the media, and it also maintains long-term archives of earthquake data for scientific and engineering research. It also conducts and supports research on long-term seismic hazards, USGS has released the UCERF California earthquake forecast. The USGS National Geomagnetism Program monitors the magnetic field at magnetic observatories and distributes magnetometer data in real time, the USGS operates the streamgaging network for the United States, with over 7400 streamgages. Real-time streamflow data are available online, since 1962, the Astrogeology Research Program has been involved in global, lunar, and planetary exploration and mapping. USGS operates a number of related programs, notably the National Streamflow Information Program. USGS Water data is available from their National Water Information System database
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S-type asteroid
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S-type asteroids, or silicaceous asteroids, are of a stony composition, hence the name. Approximately 17% of asteroids are of type, making it the second most common after the C-type. S-types are moderately bright and consist mainly of iron- and magnesium-silicates and they are dominant in the inner asteroid belt within 2.2 AU, common in the central belt within about 3 AU, but become rare farther out. The largest is 15 Eunomia, with the next largest members by diameter being 3 Juno,29 Amphitrite,532 Herculina and 7 Iris. Their spectrum has a steep slope at wavelengths shorter than 0.7 µm. The 1 µm absorption is indicative of the presence of silicates, often there is also a broad but shallow absorption feature centered near 0.63 µm. The composition of asteroids is similar to a variety of stony meteorites which share similar spectral characteristics. This whole S assemblage of asteroids is spectrally quite distinct from the carbonaceous C-group, Asteroid spectral types L-type asteroid K-type asteroid X-type asteroid Bus, S. J. Binzel, R. P. Phase II of the Small Main-belt Asteroid Spectroscopy Survey, A feature-based taxonomy
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Volatiles
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In planetary science, volatiles are the group of chemical elements and chemical compounds with low boiling points that are associated with a planets or moons crust or atmosphere. Examples include nitrogen, water, carbon dioxide, ammonia, hydrogen, methane, in astrogeology, these compounds, in their solid state, often comprise large proportions of the crusts of moons and dwarf planets. In contrast with volatiles, elements and compounds with high boiling points are known as refractory substances, the terms gas and ice in this context can apply to compounds that may be solids, liquids or gases. The Moon is very low in volatiles, its crust contains oxygen chemically bound into the rocks, in igneous petrology the term more specifically refers to the volatile components of magma that affect the appearance and explosivity of volcanoes. Volatiles in a magma with a high viscosity, generally felsic with a silica content. Volatiles in a magma with a low viscosity, generally mafic with a silica content, tend to vent. Some volcanic eruptions are explosive because the mixing water and magma reaching the surface, releases energy suddenly. Moreover, in cases, the eruption is caused by volatiles dissolved in the magma. Approaching the surface, pressure decreases and the volatiles evolve creating bubbles that circulate in the liquid, the bubbles are connected together forming a network. This especially increments the fragmentation into small drops or spray or coagulate clots in gas, generally, 95-99% of magma is liquid rock. However, the percentage of gas present, represents a very large volume when it expands on reaching atmospheric pressure. Gas is a preponderant part in a system because it generates explosive eruptions. Magma in the mantle and lower crust have a lot of volatiles within and water, also they leak hydrogen sulfide and sulfur dioxide. Sulfur dioxide is usually possible to find in basaltic and rhyolite rocks, volcanoes also release a high amount of hydrogen chloride and hydrogen fluoride as volatiles. There are three factors that effect the dispersion of volatiles in magma, confining pressure, composition of magma. Pressure and composition are the most important parameters, to understand how the magma behaves rising the surface, the role of solubility within the magma must be known. An empirical law has used for different magma-volatiles combination. For instance, for water in magma the equation is n=0.1078 P where n is the amount of dissolved gas as weight percentage, the value changes for example for water in rhyolite where n=0.4111 P and for the carbon dioxide is n=0.0023 P
28.
Geminids
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The Geminids are a meteor shower caused by the object 3200 Phaethon, which is thought to be a Palladian asteroid with a rock comet orbit. This would make the Geminids, together with the Quadrantids, the major meteor showers not originating from a comet. The meteors from this shower are slow moving, can be seen in December and usually peak around December 13–14, with the date of highest intensity being the morning of December 14. The shower is thought to be intensifying every year and recent showers have seen 120–160 meteors per hour under optimal conditions, Geminids were first observed in 1862, much more recently than other showers such as the Perseids and Leonids. The meteors in this shower appear to come from a radiant in the constellation Gemini, however, they can appear almost anywhere in the night sky, and often appear yellowish in hue. Well north of the equator, the radiant rises about sunset, in the southern hemisphere, the radiant appears only around local midnight or so. Observers in the northern hemisphere will see higher Geminid rates as the radiant is higher in the sky, the meteors travel at medium speed in relation to other showers, at about 22 miles per second, making them fairly easy to spot. The Geminids are now considered by many to be the most consistent, Geminids disintegrate while at heights above 38 kilometres
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Earth-grazing fireball
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An Earth-grazing fireball is a fireball, a very bright meteor that enters Earth’s atmosphere and leaves again. Some fragments may impact Earth as meteorites, if the meteor starts to break up or explodes in mid-air and these phenomena are then called Earth-grazing meteor processions and bolides. Famous examples of Earth-grazers are the 1972 Great Daylight Fireball and the Meteor Procession of July 20,1860. As an Earth-grazer passes through the atmosphere its mass and velocity are changed, so that its orbit, as it re-enters space, there is no agreed-upon end to the upper atmosphere, but rather incrementally thinner air from the stratosphere, mesosphere, and thermosphere up to the exosphere. For example, a meteoroid can become a meteor at an altitude of 85–120 km above the Earth, an Earth-grazing fireball is a rarely measured kind of fireball caused by a meteoroid that collides with the Earth but survives the collision by passing through, and exiting, the atmosphere. As of 2008 four grazers have been scientifically observed, october 13,1990, a 40 kilogram,41.5 km/s meteoroid passed at 97.9 km above Czechoslovakia. March 29,2006, fireball passed 18.8 km/s through the atmosphere 71 and it was the faintest Earth-grazing meteor reported in the scientific literature and the first one belonging to a meteor shower. December 24,2014, a slow moving Christmas Eve fireball SPMN241214 passed over north Africa, Spain and Portugal, List of asteroid close approaches to Earth List of Earth-crossing minor planets Meteoroid Cyrillids Fireball of 1860 Fireball of 1972
30.
Oxford English Dictionary
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The Oxford English Dictionary is a descriptive dictionary of the English language, published by the Oxford University Press. The second edition came to 21,728 pages in 20 volumes, in 1895, the title The Oxford English Dictionary was first used unofficially on the covers of the series, and in 1928 the full dictionary was republished in ten bound volumes. In 1933, the title The Oxford English Dictionary fully replaced the name in all occurrences in its reprinting as twelve volumes with a one-volume supplement. More supplements came over the years until 1989, when the edition was published. Since 2000, an edition of the dictionary has been underway. The first electronic version of the dictionary was available in 1988. The online version has been available since 2000, and as of April 2014 was receiving two million hits per month. The third edition of the dictionary will probably appear in electronic form, Nigel Portwood, chief executive of Oxford University Press. As a historical dictionary, the Oxford English Dictionary explains words by showing their development rather than merely their present-day usages, therefore, it shows definitions in the order that the sense of the word began being used, including word meanings which are no longer used. The format of the OEDs entries has influenced numerous other historical lexicography projects and this influenced later volumes of this and other lexicographical works. As of 30 November 2005, the Oxford English Dictionary contained approximately 301,100 main entries, the dictionarys latest, complete print edition was printed in 20 volumes, comprising 291,500 entries in 21,730 pages. The longest entry in the OED2 was for the verb set, as entries began to be revised for the OED3 in sequence starting from M, the longest entry became make in 2000, then put in 2007, then run in 2011. Despite its impressive size, the OED is neither the worlds largest nor the earliest exhaustive dictionary of a language, the Dutch dictionary Woordenboek der Nederlandsche Taal is the worlds largest dictionary, has similar aims to the OED and took twice as long to complete. Another earlier large dictionary is the Grimm brothers dictionary of the German language, begun in 1838, the official dictionary of Spanish is the Diccionario de la lengua española, and its first edition was published in 1780. The Kangxi dictionary of Chinese was published in 1716, trench suggested that a new, truly comprehensive dictionary was needed. On 7 January 1858, the Society formally adopted the idea of a new dictionary. Volunteer readers would be assigned particular books, copying passages illustrating word usage onto quotation slips, later the same year, the Society agreed to the project in principle, with the title A New English Dictionary on Historical Principles. He withdrew and Herbert Coleridge became the first editor, on 12 May 1860, Coleridges dictionary plan was published and research was started
31.
Oxford University Press
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Oxford University Press is the largest university press in the world, and the second oldest after Cambridge University Press. It is a department of the University of Oxford and is governed by a group of 15 academics appointed by the known as the delegates of the press. They are headed by the secretary to the delegates, who serves as OUPs chief executive, Oxford University has used a similar system to oversee OUP since the 17th century. The university became involved in the print trade around 1480, and grew into a printer of Bibles, prayer books. OUP took on the project became the Oxford English Dictionary in the late 19th century. Moves into international markets led to OUP opening its own offices outside the United Kingdom, by contracting out its printing and binding operations, the modern OUP publishes some 6,000 new titles around the world each year. OUP was first exempted from United States corporation tax in 1972, as a department of a charity, OUP is exempt from income tax and corporate tax in most countries, but may pay sales and other commercial taxes on its products. The OUP today transfers 30% of its surplus to the rest of the university. OUP is the largest university press in the world by the number of publications, publishing more than 6,000 new books every year, the Oxford University Press Museum is located on Great Clarendon Street, Oxford. Visits must be booked in advance and are led by a member of the archive staff, displays include a 19th-century printing press, the OUP buildings, and the printing and history of the Oxford Almanack, Alice in Wonderland and the Oxford English Dictionary. The first printer associated with Oxford University was Theoderic Rood, the first book printed in Oxford, in 1478, an edition of Rufinuss Expositio in symbolum apostolorum, was printed by another, anonymous, printer. Famously, this was mis-dated in Roman numerals as 1468, thus apparently pre-dating Caxton, roods printing included John Ankywylls Compendium totius grammaticae, which set new standards for teaching of Latin grammar. After Rood, printing connected with the university remained sporadic for over half a century, the chancellor, Robert Dudley, 1st Earl of Leicester, pleaded Oxfords case. Some royal assent was obtained, since the printer Joseph Barnes began work, Oxfords chancellor, Archbishop William Laud, consolidated the legal status of the universitys printing in the 1630s. Laud envisaged a unified press of world repute, Oxford would establish it on university property, govern its operations, employ its staff, determine its printed work, and benefit from its proceeds. To that end, he petitioned Charles I for rights that would enable Oxford to compete with the Stationers Company and the Kings Printer and these were brought together in Oxfords Great Charter in 1636, which gave the university the right to print all manner of books. Laud also obtained the privilege from the Crown of printing the King James or Authorized Version of Scripture at Oxford and this privilege created substantial returns in the next 250 years, although initially it was held in abeyance. The Stationers Company was deeply alarmed by the threat to its trade, under this, the Stationers paid an annual rent for the university not to exercise its full printing rights – money Oxford used to purchase new printing equipment for smaller purposes
32.
International Standard Book Number
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The International Standard Book Number is a unique numeric commercial book identifier. An ISBN is assigned to each edition and variation of a book, for example, an e-book, a paperback and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, the method of assigning an ISBN is nation-based and varies from country to country, often depending on how large the publishing industry is within a country. The initial ISBN configuration of recognition was generated in 1967 based upon the 9-digit Standard Book Numbering created in 1966, the 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108. Occasionally, a book may appear without a printed ISBN if it is printed privately or the author does not follow the usual ISBN procedure, however, this can be rectified later. Another identifier, the International Standard Serial Number, identifies periodical publications such as magazines, the ISBN configuration of recognition was generated in 1967 in the United Kingdom by David Whitaker and in 1968 in the US by Emery Koltay. The 10-digit ISBN format was developed by the International Organization for Standardization and was published in 1970 as international standard ISO2108, the United Kingdom continued to use the 9-digit SBN code until 1974. The ISO on-line facility only refers back to 1978, an SBN may be converted to an ISBN by prefixing the digit 0. For example, the edition of Mr. J. G. Reeder Returns, published by Hodder in 1965, has SBN340013818 -340 indicating the publisher,01381 their serial number. This can be converted to ISBN 0-340-01381-8, the check digit does not need to be re-calculated, since 1 January 2007, ISBNs have contained 13 digits, a format that is compatible with Bookland European Article Number EAN-13s. An ISBN is assigned to each edition and variation of a book, for example, an ebook, a paperback, and a hardcover edition of the same book would each have a different ISBN. The ISBN is 13 digits long if assigned on or after 1 January 2007, a 13-digit ISBN can be separated into its parts, and when this is done it is customary to separate the parts with hyphens or spaces. Separating the parts of a 10-digit ISBN is also done with either hyphens or spaces, figuring out how to correctly separate a given ISBN number is complicated, because most of the parts do not use a fixed number of digits. ISBN issuance is country-specific, in that ISBNs are issued by the ISBN registration agency that is responsible for country or territory regardless of the publication language. Some ISBN registration agencies are based in national libraries or within ministries of culture, in other cases, the ISBN registration service is provided by organisations such as bibliographic data providers that are not government funded. In Canada, ISBNs are issued at no cost with the purpose of encouraging Canadian culture. In the United Kingdom, United States, and some countries, where the service is provided by non-government-funded organisations. Australia, ISBNs are issued by the library services agency Thorpe-Bowker
33.
B612 Foundation
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The B612 Foundation is a private nonprofit foundation headquartered in Menlo Park, California, United States, dedicated to planetary defense against asteroids and other near-Earth object impacts. It is led mainly by scientists, former astronauts and engineers from the Institute for Advanced Study, Southwest Research Institute, Stanford University, NASA and the space industry. In 2012, the foundation announced it would design and build a privately financed asteroid-finding space observatory, fund raising has been very slow—raising only US$3 million in 2012 and 2013—and, as of June 2015, NASA is re-examining its reliance on private sector approach to space-based NEO survey missions. The B612 Foundation is named for the home of the eponymous hero of Antoine de Saint-Exupérys The Little Prince. When an asteroid enters the atmosphere it becomes known as a meteor. While basketball-sized meteors occur almost daily, and compact car-sized ones about yearly, they burn up or explode high above the Earth as bolides. The asteroid that produced the Barringer Crater was only about 46 meters in size, tsunamis can also occur after a medium-sized or larger asteroid impacts an ocean surface or other large body of water. The probability of an asteroid hitting Earth during the 21st century has been estimated at about 30%. Since the Earth is currently more populated than in previous eras, however, as of the early 2010s, only about a half of one per cent of Tunguska-type NEOs had been located by astronomers using ground-based telescope surveys. The need for an asteroid detection program has been compared to the need for monsoon, typhoon, B612 is one of several organizations to propose detailed dynamic surveys of NEOs and preventative measures such as asteroid deflection. Other groups include Chinese researchers, NASA in the United States, NEOShield in Europe, the Foundation evolved from an informal one-day workshop on asteroid deflection strategies during October 2001, organized by Dutch astrophysicist Piet Hut along with physicist and then-U. S. Astronaut Ed Lu, presented at NASAs Johnson Space Center in Houston, all were interested in contributing to the proposed creation of an asteroid deflection capability. The seminar participants included Rusty Schweickart, a former Apollo astronaut, and Clark Chapman, among the proposed experimental research missions discussed were the alteration of an asteroids spin rate, as well as changing the orbit of one part of a binary asteroid pair. Following the seminars round-table discussions the workshop generally agreed that the vehicle of choice would be powered by a low-thrust ion plasma engine. Landing a nuclear-powered plasma engined pusher vehicle on the surface was seen as promising. The October 2001 asteroid deflection workshop participants created the B612 Project to further their research. Schweickart, along with Drs. Hut, Lu and Chapman, then formed the B612 Foundation on October 7,2002, Schweickart became an early public face of the foundation and served as Chair on its board of directors. That recommended level of support would permit up to 10–20 years of advance warning in order to create a sufficient window for the required trajectory deflection
34.
1490 Ch'ing-yang event
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The Ching-yang event of 1490 is a presumed meteor shower or air burst in Qìngyáng in March or April 1490. The area was in the district of Shaanxi, if a meteor shower did occur, it may have been the result of the disintegration of an asteroid during an atmospheric entry air burst. A large number of deaths were recorded in historical Chinese accounts of the meteor shower, in the same year, Asian astronomers coincidentally discovered comet C/1490 Y1, a possible progenitor of the Quadrantid meteor showers. At least three surviving Chinese historical records describe a shower during which fell like rain, killing more than 10,000 people. At least one report of the event is found in the official History of the Ming Dynasty, but the official Ming Dynasty history omits the number of casualties, which has been frequently either doubted or discounted by present-day researchers. However Kevin Yau et al. of NASAs Jet Propulsion Laboratory did note several similarities of the Ching-yang meteor fall to the Tunguska event, one surviving account records, Stones fell like rain in the Ch’ing-yang district. The larger ones were 4 to 5 catties, and the ones were 2 to 3 catties. The larger ones were like gooses eggs and the ones were like water-chestnuts. More than 10,000 people were struck dead, all of the people in the city fled to other places. Additionally there are records of it in local gazettes and histories of the region, the History of Ming work states only that there was a rain of uncountable stones of various sizes. The large objects were as big as an egg. The date given was the lunar month of 1490, which translates as March 21 to April 19,1490. Although the Ming Dynasty history did not record the number of deaths or injuries, one semi-official document recorded that a provincial Shaanxi official reported there had been a rain of stones that weighed as much as 4–5 jin, down to 2–3 jin. The number of deaths in this account was in the tens of thousands. The semi-official report and two others date the event to the lunar month with one source dating the event as April 4,1490. Modeling Asteroid Impact Tsunami, Science of Tsunami Hazards,1998, lewis, John S. Comet And Asteroid Impact Hazards On A Populated Earth, Computer Modeling, Volume 1, Academic Press,2000, ISBN0124467601, ISBN 978-0124467606. Paine, M. Asteroid Impacts, The Extra Hazard Due To Tsunami, Science of Tsunami Hazards, Vol.17, No.3 pp. 155–166. Rogue Asteroids and Doomsday Comets, The Search for the Million Megaton Menace That Threatens Life on Earth, Wiley & Sons,1995, ISBN0471193380, ISBN 978-0-4711-9338-8
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1783 Great Meteor
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The 1783 Great Meteor was an unusually bright bolide observed on 18 August 1783, from the British Isles at a time when such phenomena were not well understood. The meteor was the subject of discussion in the Philosophical Transactions of the Royal Society and was the subject of a detailed study by Charles Blagden. The event occurred between 21,15 and 21,30 on 18 August 1783, a clear, dry night. Perhaps the most prominent was Tiberius Cavallo, an Italian natural philosopher who had happened to be amongst a group of people on the terrace at Windsor Castle at the time the meteor appeared. Every object appeared very distinct, the face of the country, in that beautiful prospect before the terrace. Other accounts, such as those of Alexander Aubert and Richard Lovell Edgeworth, noted red, one of Cavallos five companions on the terrace was the artist Thomas Sandby, who in collaboration with his brother Paul based a now well-known engraving on the event. A print of this engraving is in the collection of the Hunterian Museum, a second engraving was produced by a schoolmaster, Henry Robinson, who observed the meteor from the village of Winthorpe, Nottinghamshire. Further engravings, based on the drawings of the authors and presented in a form, were included with articles by Cavallo. Further work by Jay Pasachoff and Roberta Olson has suggested that the painting is not in fact by Scott, in support of this, in 2008 the terrestrial age of the Hambleton meteorite was determined to be 225 years
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1860 Great Meteor
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The 1860 Great Meteor procession occurred on July 20,1860. It was a unique meteoric phenomenon reported from locations across the United States, american landscape painter Frederic Church saw and painted a spectacular string of fireball meteors cross the Catskill evening sky, an extremely rare Earth-grazing meteor procession. It is believed that this was the event referred to in the poem Year of Meteors, 1859-60,150 years later in 2010 it was determined to be an Earth-grazing meteor procession. 1783 Great Meteor 1913 Great Meteor Procession 1972 Great Daylight Fireball
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1913 Great Meteor Procession
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The 1913 Great Meteor Procession occurred on February 9,1913. The meteors were particularly unusual in that there was no apparent radiant, john A. OKeefe, who conducted several studies of the event, proposed that the meteors should be referred to as the Cyrillids, in reference to the feast day of Cyril of Alexandria. The evening of February 9 was cloudy across much of the populated northeast United States. Nevertheless, more than a hundred individual reports – largely from more areas of Canada – were later collected by Clarence Chant. At around 21hr EST, witnesses were surprised to see a procession of between 40 and 60 bright, slow-moving fireballs moving from horizon to horizon in a practically identical path. Individual fireballs were visible for at least 30 to 40 seconds, and they were throwing out a constant stream of sparks and after they had passed they shot out balls of fire straight ahead that travelled more rapidly than the main bodies. They seemed to pass slowly and were in sight about five minutes. Immediately after their disappearance in the southeast a ball of clear fire and this ball did not have a tail or show sparks of any kind. Instead of being yellow like the meteors, it was clear like a star, research carried out in the 1950s by Alexander D. Mebane uncovered a handful of reports from newspaper archives in the northern United States. At Escanaba, Michigan, the Press stated the end of the world was apprehended by many as numerous meteors travelled across the northern horizon. In Batavia, New York, a few observers saw the meteors and many people heard a noise, while other reports were made in Nunda-Dansville, New York and Osceola. One observer, an A. W. Brown from Thamesville, Ontario, william Henry Pickering noted that at eight stations in Canada a trembling of the house or ground was felt. In many other places loud, thunder-like sounds were heard, occasionally by people who had not seen the meteors themselves, Pickering used the sound reports to perform a check on the height of the meteors, which he calculated at 35 miles. The first detailed study of the reports was produced by the Canadian astronomer Clarence Chant, the orbit was later discussed by Pickering and G. J. Burns, who concluded that it was essentially satellitic. This theory was a development of OKeefes unusual hypothesis on the origin of tektites, condon Report, Conception, The Great Fireball of 9 February 1913, pp. 960–2
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Chicora meteor
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Chicora is a borough in Butler County, Pennsylvania, United States. The population was 1,043 at the 2010 census, Chicora is located at 40°56′58″N 79°44′33″W, along the upper reaches of Buffalo Creek. Pennsylvania Route 68 passes through the borough, leading east 9 miles to East Brady on the Allegheny River and southwest 11 miles to Butler, according to the United States Census Bureau, Chicora has a total area of 0.54 square miles, all of it land. As of the census of 2000, there were 1,021 people,419 households, the population density was 1,841.9 people per square mile. There were 463 housing units at a density of 835.3 per square mile. The racial makeup of the borough was 99. 51% White,0. 20% African American and 0. 29% Native American. 29. 4% of all households were made up of individuals, the average household size was 2.43 and the average family size was 3.02. In the borough the population was out, with 26. 5% under the age of 18,4. 2% from 18 to 24,27. 5% from 25 to 44,24. 8% from 45 to 64. The median age was 38 years, for every 100 females there were 87.0 males. For every 100 females age 18 and over, there were 86.1 males, the median income for a household in the borough was $33,000, and the median income for a family was $39,375. Males had an income of $32,143 versus $21,875 for females. The per capita income for the borough was $17,815, about 3. 5% of families and 7. 0% of the population were below the poverty line, including 7. 4% of those under age 18 and 8. 8% of those age 65 or over. Karns City Area School District – public school Karns City High School On June 24,1938, named the Chicora Meteor, the 450+ tonne meteorite exploded approximately 12 miles above the Earths surface. Only two fragments of the meteorite were found following initial investigations and they had masses of 242g and 61g, and were discovered some miles short of the calculated point of impact of the main mass – which is yet to be found. Two more small fragments were found nearby in 1940, numerous reports of the Chicora Meteor mention that a cow was struck and injured by a falling stone, other accounts say that the cow was killed by the stone. The meteor was an olivine-hypersthene chondrite and its remains were split between the Carnegie Museum of Natural History and the Smithsonian Institution. If it had landed on Pittsburgh there would have been few survivors, they stated
39.
Sikhote-Alin meteorite
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An iron meteorite fell on the Sikhote-Alin Mountains, in southeastern Russia, in 1947. Though large iron meteorite falls had been witnessed previously and fragments recovered, an estimated 70 tonnes of material survived the fiery passage through the atmosphere and reached the Earth. The bright flash and the sound of the fall were observed for 300 kilometres around the point of impact not far from Luchegorsk. A smoke trail, estimated at 32 km long, remained in the sky for several hours, as the meteor, traveling at a speed of about 14 km/s, entered the atmosphere, it began to break apart, and the fragments fell together. At an altitude of about 5.6 km, the largest mass apparently broke up in a violent explosion called an air burst, on November 20,1957 the Soviet Union issued a stamp for the 10th anniversary of the Sikhote-Alin meteorite shower. It reproduces a painting by P. I, medvedev, a Soviet artist who witnessed the fall, he was sitting in his window starting a sketch when the fireball appeared, so he immediately began drawing what he saw. Because the meteor fell during daytime, it was observed by many eyewitnesses, evaluation of this observational data allowed V. G. Fesenkov, then chairman of the meteorite committee of the USSR Academy of Science, to estimate the meteoroids orbit before it encountered the Earth. This orbit was ellipse-shaped, with its point of greatest distance from the sun situated within the asteroid belt, such an orbit was probably created by collisions within the asteroid belt. Sikhote-Alin is a fall with the overall size of the meteoroid estimated at approximately 90,000 kg. A more recent estimate by Tsvetkov puts the mass at around 100,000 kg, krinov had estimated the post-atmospheric mass of the meteoroid at some 23,000 kg. The strewn field for this meteorite covered an area of about 1.3 km2. Some of the fragments made impact craters, the largest of which was about 26 m across and 6 m deep, fragments of the meteorite were also driven into the surrounding trees. The Sikhote-Alin meteorite is classified as an iron meteorite belonging to the chemical group IIAB and with a coarse octahedrite structure. It is composed of approximately 93% iron,5. 9% nickel,0. 42% cobalt,0. 46% phosphorus, minerals present include taenite, plessite, troilite, chromite, kamacite, and schreibersite. These pieces are characterized by regmaglypts in the surface of each specimen, the second type are fragments which were either torn apart during the atmospheric explosions or blasted apart upon impact on the frozen ground. Most were probably the result of the explosion at 5.6 km altitude, a large specimen is on display in Moscow. Many other specimens are held by Russian Academy of Science and a number of smaller specimens have made their way into the collectors market. Glossary of meteoritics Meteorite Meteorite fall 2013 Russian meteor event List of meteor air bursts Exposition Meteorites, Moscow, Russia, Russian Academy of Sciences
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Murchison meteorite
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The Murchison meteorite is a large meteorite that fell to earth near Murchison, Victoria, in Australia, in 1969. It is one of the most studied meteorites due to its mass, the fact that it was a fall. About 30 seconds later, a tremor was heard, many fragments were found over an area larger than 13 km², with individual mass up to 7 kg, one, weighing 680 g, broke through a roof and fell in hay. The total collected mass exceeds 100 kg, the meteorite belongs to the CM group of carbonaceous chondrites. Like most CM chondrites, Murchison is petrologic type 2, which means that it experienced extensive alteration by water-rich fluids on its parent body before falling to Earth, CM chondrites, together with the CI group, are rich in carbon and are among the most chemically primitive meteorites. Like other CM chondrites, Murchison contains abundant CAIs, over 15 amino acids, some of the basic components of life, have been identified in the meteorite by multiple studies. Murchison contains common amino acids such as glycine, alanine and glutamic acid as well as unusual ones like isovaline and pseudoleucine, a complex mixture of alkanes was isolated as well, similar to that found in the Miller–Urey experiment. Serine and threonine, usually considered to be earthly contaminants, were absent in the samples. A specific family of amino acids called diamino acids was identified in the Murchison meteorite as well, the initial report stated that the amino acids were racemic and therefore formed in an abiotic manner because amino acids of terrestrial proteins are all of the L-configuration. In 1997, L-excesses were also found in an amino acid, isovaline. At the same time, L-excesses of alanine were again found in Murchison but now with enrichment in the isotope 15N, however, the list of organic materials identified in the meteorite was extended to polyols by 2001. Although the meteorite contained a mixture of left-handed and right-handed amino acids, most amino acids used by living organisms are left-handed in chirality, and most sugars used are right-handed. A team of chemists in Sweden demonstrated in 2005 that this homochirality could have triggered or catalyzed. Several lines of evidence indicate that the portions of well-preserved fragments from Murchison are pristine. A2010 study using high resolution analytical tools including spectroscopy, identified 14,000 molecular compounds including 70 amino acids in a sample of the meteorite, measured purine and pyrimidine compounds were found in the Murchison meteorite. Carbon isotope ratios for uracil and xanthine of δ13C = +44. 5‰ and +37. 7‰, respectively and this specimen demonstrates that many organic compounds were delivered by early Solar System bodies and may have played a key role in lifes origin. Cosmochemistry Glossary of meteoritics Rosenthal, Anne M. Murchisons Amino Acids, meteorite That Fell in 1969 Still Revealing Secrets of the Early Solar System. This article incorporates public domain material from websites or documents of the National Aeronautics and Space Administration
41.
1972 Great Daylight Fireball
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The Great Daylight Fireball was an Earth-grazing fireball that passed within 57 kilometres of Earths surface at 20,29 UTC on August 10,1972. It entered Earths atmosphere at a speed of 15 kilometres per second in daylight over Utah, United States and passed northwards leaving the atmosphere over Alberta and it was seen by many people and recorded on film and by space-borne sensors. An eyewitness to the event, located in Missoula, Montana, saw the pass directly overhead. The smoke trail lingered in the atmosphere for several minutes, the atmospheric pass modified the objects mass and orbit around the Sun, but it is probably still in an Earth-crossing orbit and passed close to Earth again in August 1997. IAUs website states that these suggestions have not been substantiated, analysis of its appearance and trajectory showed the object was about 3–14 m in diameter, depending on whether it was a comet made of ices, or a stony and therefore denser asteroid. Other sources identified it as an Apollo asteroid in an Earth-crossing orbit that would make a subsequent close approach to Earth in August 1997 and its velocity was reduced by about 800 metres per second and the encounter significantly changed its orbital inclination from 15 degrees to 7 degrees. The US19720810 meteoroid is described in the preface of the first chapter of Arthur C, the clip featuring the fireball is shown in the 1994 made-for-TV film Without Warning, in which it is described as a 500-metre asteroid narrowly missing the Earth by thousands of feet
42.
Earth-grazing meteoroid of 13 October 1990
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On 13 October 1990, meteoroid EN131090, with an estimated mass of 44 kg, entered the Earths atmosphere above Czechoslovakia and Poland and, after a few seconds, returned to space. The encounter with Earth significantly changed its orbit and, to a smaller extent, visual observations were reported by three independent Czech observers, astronomer Petr Pravec, Pavel Klásek, and Lucie Bulíčková. According to their report, the event started at 03,27, 16±3 UT and it left a track that was visible for 10 seconds. Most data about the encounter were acquired using photographic observations by cameras of the European Fireball Network, both were equipped with all-sky fisheye objectives. The Červená hora image was especially valuable and it recorded the fireballs trajectory over approximately 110°, starting 51° above the southern horizon, passing the zenith just 1° westward and disappearing only 19° above the northern horizon. Its camera was equipped with a rotating shutter that interrupted the exposure 12.5 times per second and divided the captured track of the fireball. Over the last 4°, the angular velocity was lower than the resolution of the instrument. The Svratouch image recorded the only for about 15°, beginning at 30° above the northwest horizon. Despite this, the data were sufficient for the calculations, gotfred M. Kristensen also detected the fireball in Havdrup, Denmark, using a pen recorder connected to a radio receiver for 78 seconds, at 03,27, 24±6 UT. The meteoroid grazed Earths atmosphere quite gently and it would probably still have been visible until it reached a height of 110 km above the southern Baltic Sea. The meteoroids absolute magnitude was approximately −6 and did not vary significantly during the few seconds of observation and it traveled a distance of 409 km in 9.8 seconds during the time it was observed. It moved at a speed of 41.74 km per second and this small loss of speed,12 m per second, corresponded to a loss of kinetic specific energy of 0.5 MJ/kg, which was converted to heat. The change in the velocity vector due to Earths gravity during the hours it was in the earths vicinity was on the order of kilometres per second. The software also calculated the fireballs instantaneous apparent magnitude at the ground, the computation started and ended with heights of approximately 250 km, long before and after the cameras of the European Fireball Network could observe it. Its apparent magnitude started at a value of +5.7, the program gave an apparent magnitude of −5.7 when it was seen by one camera and −6.3 at perigee. The fireball subsequently dimmed, with an apparent magnitude of −5.4 when it was last seen by the cameras and these values are not entirely certain, because the program worked with the simplified assumption that the luminous efficacy of the fireball did not change along the track. The starting apparent magnitude is not far from the naked eye visibility limits, for example, faint stars of the magnitude +6 can be observed only in dark rural areas approximately 150 km away from large cities. This magnitude corresponds to the apparent magnitude of Uranus, at its brightest, it was several times as bright as the maximum brightness of Venus
43.
2002 Eastern Mediterranean event
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The 2002 Eastern Mediterranean Event was a high-energy upper atmosphere explosion over the Mediterranean Sea, around 34°N 21°E on June 6,2002. This explosion, similar in power to an atomic bomb, has been related to a small asteroid undetected while approaching Earth. The object disintegrated in an air burst impact and no meteorite fragments were recovered, the air burst occurred over the sea. Impact event List of meteor air bursts Near-Earth object Potentially hazardous asteroid Vela incident
44.
2002 Vitim event
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The 2002 Vitim event or Bodaybo event is believed to be an impact by a bolide in the Vitim River basin. It occurred near the town of Bodaybo in the Mamsko-Chuisky district of Irkutsk Oblast, the event was detected by a US military missile-defense satellite. Attempts were made to define the magnitude of the explosion, U. S. military analysts calculated it was around 0.86 terajoules. Peter Brown estimates the yield of both Bodiabo and Tagish Lake at about 2 kilotons—a factor of roughly 10,000 less than the Tunguska event. Russian physicist Andrey Olkhovatov estimates it at 4–5 kilotons, information about the event appeared in the mass media and among scientists after only a week. A small expedition, sent by the Institute of Sun–Earth Physics, 1st - Russian MChS team tried to find an object near Bodaybo. 2nd - October,2002 expedition of Irkutsk State University, official expeditions in 2002–2003 never reached the impact site, situated in a remote Siberian taiga. As reported by the ufology organization Kosmopoisk, in May 2003 an expedition, the situation there looked similar to that of the Podkamennaya Tunguska River after the Tunguska event in 1908. Snow and water samples were analyzed and found to contain an amount of tritium, as well as radioactive isotopes of cobalt. Chernobrov suggested that the Vitim event could be caused by a low density comet nucleus with a diameter of about 30–100 meters, cash plea for space impact study. Siberia meteorite flattens 40 sq miles, archived from the original on March 10,2007. Some atmospheric and magnetospheric effects possibly related to the Vitim bolide impact, chernobrov, Vadim & Soleny, Alexander & Lawrence, Maria
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2007 Carancas impact event
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The Carancas impact event refers to the fall of the Carancas chondritic meteorite on September 15,2007, near the village of Carancas in Peru, close to the Bolivian border and Lake Titicaca. The impact created a crater and scorched earth around its location, a local official, Marco Limache, said that boiling water started coming out of the crater, and particles of rock and cinders were found nearby, as fetid, noxious gases spewed from the crater. Surface impact occurred above 3,800 m, after the impact, villagers who had approached the impact site grew sick from a then-unexplained illness, with a wide array of symptoms. Two days later, Peruvian scientists confirmed that there had indeed been a meteorite strike, at that point, no further information on the cause of the mystery illness was known. At 11,40,14 local time on 15 September 2007, the impact created a crater larger than 4.5 m deep,13 m wide, with visibly scorched earth around the impact site. A local official, Marco Limache, said that boiling water started coming out of the crater, the crater size was given as 13.80 by 13.30 m, with its greatest dimensions in an east-west direction. The fireball had been observed by the locals as strongly luminous with a smoky tail, the object moved in a direction toward N030E. The small seismic shock of the impact shattered the windows of the health center 1-kilometer away. A smoke column was formed at the site that lasted several minutes, one villager was as close as 100 m from the impact site. He fell from his bicycle but was not injured, a small building 120 m from the impact site did not suffer much either besides roof damage from flying debris. Soon after the impact, over 600 villagers visited the site and some began to fall ill from unexplained causes, including symptoms of dermal injuries, nausea, headaches, diarrhea and vomiting. On 20 September, Peruvian scientists confirmed that there had been a meteorite strike, Impact crater specialists have called the impact unusual, and have stated that the meteorite was at least 3 m in diameter before breaking up. According to cosmochemist Larry Grossman of the University of Chicago, the aerial lights, the loud noise and explosive impact originally led Peruvians to think that Chile had launched an attack. A report from three geologists at Peru’s Geophysics Institute was released on Thursday 20 September, astrophysicist Jose Ishitsuka confirmed that there had been a meteorite strike. They detected iron, nickel, cobalt, and traces of iridium — elements characteristic of the composition of meteorites. The quantitative proportions of silicon, aluminium, potassium, calcium, magnesium, INGEMMET of Peru released internally on September 21 a report on the Carancas meteorite fall. The release of the document to the public was delayed for one week, kamacite occurs naturally only in meteorites. The official classification of the Carancas meteorite, accepted by the Meteoritical Society, was done by a team of working at the University of Arizona
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2008 TC3
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2008 TC3 was an 80 metric tons,4.1 meters diameter asteroid that entered Earths atmosphere on October 7,2008. It exploded at an estimated 37 kilometers above the Nubian Desert in Sudan, some 600 meteorites, weighing a total of 10.5 kilograms, were recovered, many of these belonged to a rare type known as ureilites, which contain, among other minerals, nanodiamonds. It was the first time that an impact had been predicted prior to its entry into the atmosphere as a meteor. The asteroid was discovered by Richard A. Kowalski at the Catalina Sky Survey 1. 5-meter telescope at Mount Lemmon, north of Tucson, Arizona, US and it was notable as the first such body to be observed and tracked prior to reaching Earth. The process of detecting and tracking an object, an effort sometimes referred to as Spaceguard, was put to the test. On October 7,01,49 UTC, the asteroid entered the shadow of the Earth, Impact predictions were performed by University of Pisas CLOMON2 semi-automatic monitoring system as well as Jet Propulsion Laboratorys Sentry system. Spectral observations that were performed by astronomers at the 4. 2-meter William Herschel Telescope at La Palma, Canary Islands are consistent with either a C-type or M-type asteroid. It exploded tens of kilometers above the ground with the energy of 0.9 to 2.1 kilotons of TNT over an area of the Nubian Desert. The Times reported that the light was so intense that it lit up the sky like a full moon. A webcam captured the flash lighting up El-Gouna beach 725 kilometres north of the explosion, a low-resolution image of the explosion was captured by the weather satellite Meteosat 8. The Meteosat images place the fireball at 21. 00°N32. 15°E /21.00,32. 15. Infrasound detector arrays in Kenya also detected a sound wave from the direction of the expected impact corresponding to energy of 1.1 to 2.1 kilotons of TNT, asteroids of this size hit Earth about two or three times a year. These images have not been publicly released, EUMETSAT fireball images A search of the impact zone that began on December 6,2008, turned up 10.5 kilograms of rock in some 600 fragments. These meteorites are collectively named Almahata Sitta, which means Station Six in Arabic and is a station between Wadi Halfa and Khartoum, Sudan. The initial 15 meteorites were found in the first three days of the search, numerous witnesses were interviewed, and the hunt was guided with a search grid and specific target area produced by NASAs Jet Propulsion Laboratory in Pasadena, California. The first sample measured was an anomalous ultra-fine-grained porous polymict ureilite achondrite, reflectance spectra of the meteorite, combined with the astronomical observations, identified asteroid 2008 TC3 as an F-type asteroid class. These fragile anomalous dark carbon-rich ureilites are now linked to the group of F-class asteroids. Amino acids have been found on the meteorite, carbonaceous chondrites List of notable asteroids 1972 Great Daylight Fireball Impact event 2014 AA WT1190F Atkinson, N
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