1.
La Silla Observatory
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La Silla Observatory is an astronomical observatory in Chile with three telescopes built and operated by the European Southern Observatory. Several other telescopes are located at the site and are maintained by ESO. The observatory is one of the largest in the Southern Hemisphere and was the first in Chile to be used by ESO. The La Silla telescopes and instruments are located 150 km northeast of La Serena at the outskirts of the Chilean Atacama Desert, following the decision in 1963 to approve Chile as the site for the ESO observatory, scouting parties were sent to various locations to assess their suitability. The site that was decided upon was La Silla in the part of the Atacama desert,600 km north of Santiago de Chile. Besides being government property, it had the benefits of being in a dry, flat and easily accessible area, yet isolated and remote from any artificial light. Originally named the Cinchado, it was renamed La Silla after its saddle-like shape, on October 30,1964, the contracts were signed and an area of 245 square miles was purchased the following year. During 1965, temporary facilities were erected with living quarters, a workshop, the dedication ceremony of the road to the top took place in March 1966, two months after its completion. On 25 March 1969, the ESO site at La Silla was finally inaugurated by President Eduardo Frei Montalva. With a permanent base of dormitories, workshops, hotels and several functioning telescopes, the observatory was fully operational. The ESO1. 5-metre and ESO 1-metre telescopes had been erected in the late 1960s and these three telescopes can be seen in this order from right to left in the background of the adjunct image from June 1968. By 1976, the largest telescope planned, the § ESO3.6 m Telescope and it was subsequently to have a 1. 4m CAT attached. In 1984, the 2. 2m telescope began operations, while in March 1989, a 1-metre telescope owned by Marseille Observatory opened in 1998, followed by a 1. 2-metre telescope from Geneva Observatory in 2000. ESO operates three major optical and near infrared telescopes at the La Silla site, the New Technology Telescope, the 3. 6-m ESO Telescope, and these telescopes are not operated by ESO and hence do not fall under the responsibility of La Silla Science Operations. The telescope hosts HARPS, the High Accuracy Radial velocity Planet Searcher, HARPS is a spectrograph with unrivalled precision and is the most successful finder of low-mass exoplanets to date. Since April 2008, HARPS is the instrument available at the 3.6 m telescope. The ESO New Technology Telescope is an Alt-Az,3. 58-metre Richey-Chretien telescope which pioneered the use of active optics, the telescope and its enclosure had a revolutionary design for optimal image quality. NTT saw first light in March 1989, the telescope chamber is ventilated by a system of flaps which optimize the air flow across the NTT minimizing the dome and mirror seeing
2.
Minor planet
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A minor planet is an astronomical object in direct orbit around the Sun that is neither a planet nor exclusively classified as a comet. Minor planets can be dwarf planets, asteroids, trojans, centaurs, Kuiper belt objects, as of 2016, the orbits of 709,706 minor planets were archived at the Minor Planet Center,469,275 of which had received permanent numbers. The first minor planet to be discovered was Ceres in 1801, the term minor planet has been used since the 19th century to describe these objects. The term planetoid has also used, especially for larger objects such as those the International Astronomical Union has called dwarf planets since 2006. Historically, the asteroid, minor planet, and planetoid have been more or less synonymous. This terminology has become complicated by the discovery of numerous minor planets beyond the orbit of Jupiter. A Minor planet seen releasing gas may be classified as a comet. Before 2006, the IAU had officially used the term minor planet, during its 2006 meeting, the IAU reclassified minor planets and comets into dwarf planets and small Solar System bodies. Objects are called dwarf planets if their self-gravity is sufficient to achieve hydrostatic equilibrium, all other minor planets and comets are called small Solar System bodies. The IAU stated that the minor planet may still be used. However, for purposes of numbering and naming, the distinction between minor planet and comet is still used. Hundreds of thousands of planets have been discovered within the Solar System. The Minor Planet Center has documented over 167 million observations and 729,626 minor planets, of these,20,570 have official names. As of March 2017, the lowest-numbered unnamed minor planet is 1974 FV1, as of March 2017, the highest-numbered named minor planet is 458063 Gustavomuler. There are various broad minor-planet populations, Asteroids, traditionally, most have been bodies in the inner Solar System. Near-Earth asteroids, those whose orbits take them inside the orbit of Mars. Further subclassification of these, based on distance, is used, Apohele asteroids orbit inside of Earths perihelion distance. Aten asteroids, those that have semi-major axes of less than Earths, Apollo asteroids are those asteroids with a semimajor axis greater than Earths, while having a perihelion distance of 1.017 AU or less. Like Aten asteroids, Apollo asteroids are Earth-crossers, amor asteroids are those near-Earth asteroids that approach the orbit of Earth from beyond, but do not cross it
3.
Asteroid belt
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The asteroid belt is the circumstellar disc in the Solar System located roughly between the orbits of the planets Mars and Jupiter. It is occupied by numerous irregularly shaped bodies called asteroids or minor planets, the asteroid belt is also termed the main asteroid belt or main belt to distinguish it from other asteroid populations in the Solar System such as near-Earth asteroids and trojan asteroids. About half the mass of the belt is contained in the four largest asteroids, Ceres, Vesta, Pallas, the total mass of the asteroid belt is approximately 4% that of the Moon, or 22% that of Pluto, and roughly twice that of Plutos moon Charon. Ceres, the belts only dwarf planet, is about 950 km in diameter, whereas Vesta, Pallas. The remaining bodies range down to the size of a dust particle, the asteroid material is so thinly distributed that numerous unmanned spacecraft have traversed it without incident. Nonetheless, collisions between large asteroids do occur, and these can form a family whose members have similar orbital characteristics. Individual asteroids within the belt are categorized by their spectra. The asteroid belt formed from the solar nebula as a group of planetesimals. Planetesimals are the precursors of the protoplanets. Between Mars and Jupiter, however, gravitational perturbations from Jupiter imbued the protoplanets with too much energy for them to accrete into a planet. Collisions became too violent, and instead of fusing together, the planetesimals, as a result,99. 9% of the asteroid belts original mass was lost in the first 100 million years of the Solar Systems history. Some fragments eventually found their way into the inner Solar System, Asteroid orbits continue to be appreciably perturbed whenever their period of revolution about the Sun forms an orbital resonance with Jupiter. At these orbital distances, a Kirkwood gap occurs as they are swept into other orbits. Classes of small Solar System bodies in other regions are the objects, the centaurs, the Kuiper belt objects, the scattered disc objects, the sednoids. On 22 January 2014, ESA scientists reported the detection, for the first definitive time, of water vapor on Ceres, the detection was made by using the far-infrared abilities of the Herschel Space Observatory. The finding was unexpected because comets, not asteroids, are considered to sprout jets. According to one of the scientists, The lines are becoming more and more blurred between comets and asteroids. This pattern, now known as the Titius–Bode law, predicted the semi-major axes of the six planets of the provided one allowed for a gap between the orbits of Mars and Jupiter
4.
Kirkwood gap
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A Kirkwood gap is a gap or dip in the distribution of the semi-major axes of the orbits of main-belt asteroids. They correspond to the locations of orbital resonances with Jupiter, for example, there are very few asteroids with semimajor axis near 2.50 AU, period 3.95 years, which would make three orbits for each orbit of Jupiter. Other orbital resonances correspond to orbital periods whose lengths are simple fractions of Jupiters, the weaker resonances lead only to a depletion of asteroids, while spikes in the histogram are often due to the presence of a prominent asteroid family. The orbital elements of the asteroids vary chaotically as a result, the 2,1 MMR has a few relatively stable islands within the resonance, however. These islands are depleted due to slow diffusion onto less stable orbits and this process, which has been linked to Jupiter and Saturn being near a 5,2 resonance, may have been more rapid when Jupiters and Saturns orbits were closer together. More recently, a small number of asteroids have been found to possess high eccentricity orbits which do lie within the Kirkwood gaps. Examples include the Alinda family and the Griqua family and these orbits slowly increase their eccentricity on a timescale of tens of millions of years, and will eventually break out of the resonance due to close encounters with a major planet. The most prominent Kirkwood gaps are located at mean orbital radii of,2.06 AU2.5 AU, home to the Alinda family of asteroids 2.82 AU2.95 AU3.27 AU, home to the Griqua family of asteroids. Weaker and/or narrower gaps are found at,1.9 AU2.25 AU2.33 AU2.71 AU3.03 AU3.075 AU3.47 AU3.7 AU. Orbital resonance Alinda family Griqua family Article on Kirkwood gaps at Wolframs scienceworld
5.
Flora family
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The Flora or Florian family of asteroids is a large grouping of S-type asteroids in the inner main belt, whose origin and properties are relatively poorly understood at present. Roughly 4–5% of all main belt asteroids belong to this family, the Flora family of asteroids may be the source of the Chicxulub impactor, the likely culprit in the extinction of the dinosaurs. The largest member is 8 Flora, which measures 140 km in diameter, nevertheless, the parent body was almost certainly disrupted by the impact/s that formed the family, and Flora is probably a gravitational aggregate of most of the pieces. 43 Ariadne makes up much of the mass, with the remaining family members being fairly small. A noticeable fraction of the parent body has been lost from the family since the original impact, for example, it has been estimated that Flora contains only about 57% of the parent bodys mass, but about 80% of the mass in the present family. The Flora family is broad and gradually fades into the background population in such a way that its boundaries are very poorly defined. There are also several non-uniformities or lobes within the family, one cause of which may have been later secondary collisions between family members, hence, it is a classical example of a so-called asteroid clan. Curiously, the largest members,8 Flora and 43 Ariadne, are located near the edge of the family, the reason for this unusual mass distribution within the family is unknown at present. 951 Gaspra, a core family member was visited by the Galileo spacecraft on its way to Jupiter. Studies of Gaspra suggests that the age is of the order of 200 million years. The Flora family members are considered candidates for being the parent bodies of the L chondrite meteorites. The Flora family was one of the five original Hirayama families that were first identified and it has a high number of early discovered members both because S-type asteroids tend to have high albedo, and because it is the closest major asteroid grouping to Earth. A HCM numerical analysis determined a large group of family members, whose proper orbital elements lie in the approximate ranges The boundaries of the family are, however. At the present epoch, the range of osculating orbital elements of these members is Zappalas 1995 analysis found 604 core members. A search of a recent proper element database for 96944 minor planets in 2005 yielded 7438 objects lying within the region defined by the first table above. However, this includes parts of the Vesta and Nysa families in the corners so that a more likely membership estimate is 4000–5000 objects. This means that the Flora family represents 4–5% of all main belt asteroids, because of the high background density of asteroids in this part of space, one might expect that a great number of interlopers would be present. This is because interlopers are hard to distinguish family members because the family is of the same spectral type that dominates the inner main belt overall
. Bibcode:2012ApJ...759L...8M. doi:10.1088/2041-8205/759/1/L8. Retrieved 23 August 2016.
