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Rangiroa Atoll
Rangiroa ( Tuamotuan for 'vast sky') or Te Kokōta (Cook Islands Māori for 'the Hyades star cluster') is the largest atoll in the Tuamotus and one of the largest in the world (smaller than Kwajalein in the Marshall Islands and Huvadhu in the Maldives). It is in French Polynesia and is part of the Palliser group. The nearest atoll is Tikehau, to the west. It is about northeast of Tahiti. Rangiroa is home to about 2,500 people on almost . The chief town is Avatoru, in the atoll's northwest. Geography and environment The atoll consists of about 415 motus, islets and sandbars comprising a total land area of about . There are approximately one hundred narrow passages (straits or passes), called ''hoa'', in the fringing reef. The atoll has a flattened elliptic shape, with in length and a width ranging from . The width of land reaches wide and its circumference totals up to . The lagoon has a maximum depth of and its surface is . It is so large that it has its own horizo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agency of the US federal government responsible for the civil space program, aeronautics research, and space research. NASA was established in 1958, succeeding the National Advisory Committee for Aeronautics (NACA), to give the U.S. space development effort a distinctly civilian orientation, emphasizing peaceful applications in space science. NASA has since led most American space exploration, including Project Mercury, Project Gemini, the 1968-1972 Apollo Moon landing missions, the Skylab space station, and the Space Shuttle. NASA supports the International Space Station and oversees the development of the Orion spacecraft and the Space Launch System for the crewed lunar Artemis program, Commercial Crew spacecraft, and the planned Lunar Gateway space station. The agency is also responsible for the Launch Services Program, which provides oversight of launch operations and countdown management f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palliser Islands
The Palliser Islands or Pallisers are a subgroup of the Tuamotu group in French Polynesia. They are located in the very northwest of the main group of atolls. Atolls The group includes: *Apataki *Arutua *Fakarava *Kaukura *Mataiva *Rangiroa *Makatea *Tikehau *Toau Administration *Administratively, Apataki and Kaukura atolls belong to the commune of Arutua, with a total population of 1510 inhabitants. *Toau, Niau, and Fakarava, belong to the commune of Fakarava. The total population is of 1800 inhabitants. *The commune of Rangiroa consists of 3 atolls: Rangiroa itself, Tikehau and Mataiva, and a separate island (Makatea). The total population is of 3467 inhabitants. History The Palliser Islands were named "Palliser's Isles" by Captain James Cook, who was the first European to sight them, on 19 April and 20 April 1774; naming them as such in honour of Admiral Sir Hugh Palliser Admiral Sir Hugh Palliser, 1st Baronet (26 February 1723 – 19 March 1796) was a Royal Navy officer. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manta Ray
Manta rays are large rays belonging to the genus ''Mobula'' (formerly its own genus ''Manta''). The larger species, '' M. birostris'', reaches in width, while the smaller, '' M. alfredi'', reaches . Both have triangular Pectoral fin#AnchPectoral, pectoral fins, horn-shaped cephalic fins and large, forward-facing mouths. They are classified among the Myliobatiformes (stingrays and relatives) and are placed in the Family (biology), family Myliobatidae (eagle rays). They have the largest brains and brain to body ratio of all fish, and can pass the mirror test. Mantas are found in warm temperate, subtropical and tropical waters. Both species are Pelagic fish, pelagic; ''M. birostris'' Animal migration, migrates across open oceans, singly or in groups, while ''M. alfredi'' tends to be resident and coastal. They are filter feeders and eat large quantities of zooplankton, which they gather with their open mouths as they swim. However, research suggests that the majority of their die ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Tiputa Pass
Tiputa Pass is a strait in the northwest portion of Rangiroa lagoon in the Tuamotu Islands of French Polynesia, joining the lagoon to the open ocean. There are only two such passes in Rangiroa, the second one being Avatoru Pass. Tiputa Pass separates the villages of Avatoru and Tiputa. Scuba diving Tiputa Pass is a well-known scuba-diving destination. During the austral summer (December to March), great hammerhead sharks and manta rays Manta rays are large rays belonging to the genus ''Mobula'' (formerly its own genus ''Manta''). The larger species, '' M. birostris'', reaches in width, while the smaller, '' M. alfredi'', reaches . Both have triangular pectoral fins, horn-sh ... are present in the area. [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
High Tide
Tides are the rise and fall of sea levels caused by the combined effects of the gravitational forces exerted by the Moon (and to a much lesser extent, the Sun) and are also caused by the Earth and Moon orbiting one another. Tide tables can be used for any given locale to find the predicted times and amplitude (or "tidal range"). The predictions are influenced by many factors including the alignment of the Sun and Moon, the phase and amplitude of the tide (pattern of tides in the deep ocean), the amphidromic systems of the oceans, and the shape of the coastline and near-shore bathymetry (see '' Timing''). They are however only predictions, the actual time and height of the tide is affected by wind and atmospheric pressure. Many shorelines experience semi-diurnal tides—two nearly equal high and low tides each day. Other locations have a diurnal tide—one high and low tide each day. A "mixed tide"—two uneven magnitude tides a day—is a third regular category. Tides va ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lagoon
A lagoon is a shallow body of water separated from a larger body of water by a narrow landform, such as reefs, barrier islands, barrier peninsulas, or isthmuses. Lagoons are commonly divided into ''coastal lagoons'' (or ''barrier lagoons'') and ''atoll lagoons''. They have also been identified as occurring on mixed-sand and gravel coastlines. There is an overlap between bodies of water classified as coastal lagoons and bodies of water classified as estuaries. Lagoons are common coastal features around many parts of the world. Definition and terminology Lagoons are shallow, often elongated bodies of water separated from a larger body of water by a shallow or exposed shoal, coral reef, or similar feature. Some authorities include fresh water bodies in the definition of "lagoon", while others explicitly restrict "lagoon" to bodies of water with some degree of salinity. The distinction between "lagoon" and "estuary" also varies between authorities. Richard A. Davis Jr. restrict ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumference
In geometry, the circumference (from Latin ''circumferens'', meaning "carrying around") is the perimeter of a circle or ellipse. That is, the circumference would be the arc length of the circle, as if it were opened up and straightened out to a line segment. More generally, the perimeter is the curve length around any closed figure. Circumference may also refer to the circle itself, that is, the locus corresponding to the edge of a disk. The is the circumference, or length, of any one of its great circles. Circle The circumference of a circle is the distance around it, but if, as in many elementary treatments, distance is defined in terms of straight lines, this cannot be used as a definition. Under these circumstances, the circumference of a circle may be defined as the limit of the perimeters of inscribed regular polygons as the number of sides increases without bound. The term circumference is used when measuring physical objects, as well as when considering abstract g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ellipse
In mathematics, an ellipse is a plane curve surrounding two focus (geometry), focal points, such that for all points on the curve, the sum of the two distances to the focal points is a constant. It generalizes a circle, which is the special type of ellipse in which the two focal points are the same. The elongation of an ellipse is measured by its eccentricity (mathematics), eccentricity e, a number ranging from e = 0 (the Limiting case (mathematics), limiting case of a circle) to e = 1 (the limiting case of infinite elongation, no longer an ellipse but a parabola). An ellipse has a simple algebraic solution for its area, but only approximations for its perimeter (also known as circumference), for which integration is required to obtain an exact solution. Analytic geometry, Analytically, the equation of a standard ellipse centered at the origin with width 2a and height 2b is: : \frac+\frac = 1 . Assuming a \ge b, the foci are (\pm c, 0) for c = \sqrt. The standard parametric e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fringing Reef
A fringing reef is one of the three main types of coral reef. It is distinguished from the other main types, barrier reefs and atolls, in that it has either an entirely shallow backreef zone (lagoon) or none at all. If a fringing reef grows directly from the shoreline, then the reef flat extends to the beach and there is no backreef. In other cases (e.g., most of the Bahamas), fringing reefs may grow hundreds of yards from shore and contain extensive backreef areas within which it contains food and water, examples are Philippines, Indonesia, Timor-Leste, the western coast of Australia, the Caribbean, East Africa, and Red Sea. Charles Darwin believed that fringing reefs are the first kind of reefs to form around a landmass in a long-term reef growth process.Kennedy, D.M. and Woodroffe, C.D. 2002.Fringing reef growth and morphology: a review. ''Earth-Science Reviews''. 57:255-277. The largest fringing coral reef in the world is the Ningaloo Reef, stretching to around along the coas ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Straits
A strait is an oceanic landform connecting two seas or two other large areas of water. The surface water generally flows at the same elevation on both sides and through the strait in either direction. Most commonly, it is a narrow ocean channel that lies between two land masses. Some straits are not navigable, for example because they are either too narrow or too shallow, or because of an unnavigable reef or archipelago. Straits are also known to be loci for sediment accumulation. Usually, sand-size deposits occur on both the two opposite strait exits, forming subaqueous fans or deltas. Terminology The terms ''channel'', ''pass'', or ''passage'' can be synonymous and used interchangeably with ''strait'', although each is sometimes differentiated with varying senses. In Scotland, ''firth'' or ''Kyle'' are also sometimes used as synonyms for strait. Many straits are economically important. Straits can be important shipping routes and wars have been fought for control of them. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motu (geography)
An islet is a very small, often unnamed island. Most definitions are not precise, but some suggest that an islet has little or no vegetation and cannot support human habitation. It may be made of rock, sand and/or hard coral; may be permanent or tidal (i.e. surfaced reef or seamount); and may exist in the sea, lakes, rivers or any other sizeable bodies of water. Definition As suggested by its origin ''islette'', an Old French diminutive of "isle", use of the term implies small size, but little attention is given to drawing an upper limit on its applicability. The World Landforms website says, "An islet landform is generally considered to be a rock or small island that has little vegetation and cannot sustain human habitation", and further that size may vary from a few square feet to several square miles, with no specific rule pertaining to size. Other terms * Ait (/eɪt/, like eight) or eyot (/aɪ(ə)t, eɪt/), a small island. It is especially used to refer to river i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atoll
An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon partially or completely. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical oceans and seas where corals can grow. Most of the approximately 440 atolls in the world are in the Pacific Ocean. Two different, well-cited models, the subsidence and antecedent karst models, have been used to explain the development of atolls.Droxler, A.W. and Jorry, S.J., 2021. ''The Origin of Modern Atolls: Challenging Darwin's Deeply Ingrained Theory.'' ''Annual Review of Marine Science'', 13, pp.537-573. According to Charles Darwin's ''subsidence model'', the formation of an atoll is explained by the subsidence of a volcanic island around which a coral fringing reef has formed. Over geologic time, the volcanic island becomes extinct and eroded as it subsides completely beneath the surface of the ocean. As the volcanic island subsides, the coral fringing reef becomes a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
