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Rangiroa Lagoon
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 horiz ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NASA
The National Aeronautics and Space Administration (NASA ) is an independent agencies of the United States government, independent agency of the federal government of the United States, US federal government responsible for the United States's civil list of government space agencies, space program, aeronautics research and outer space, space research. National Aeronautics and Space Act, Established in 1958, it succeeded the National Advisory Committee for Aeronautics (NACA) to give the American space development effort a distinct civilian orientation, emphasizing peaceful applications in space science. It has since led most of America's space exploration programs, including Project Mercury, Project Gemini, the 1968–1972 Apollo program missions, the Skylab space station, and the Space Shuttle. Currently, NASA supports the International Space Station (ISS) along with the Commercial Crew Program and oversees the development of the Orion (spacecraft), Orion spacecraft and the Sp ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Palliser Islands
The Palliser Islands or Pallisers are a subgroup of the Tuamotus, 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, Arutua, Apataki and Kaukura atolls belong to the Communes of France, commune of Arutua, with a total population of 1510 inhabitants. *Toau 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. References Atolls of the Tuamotus Archipelagoes of the Pacific O ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Manta Ray
Manta rays are large Batoidea, rays belonging to the genus ''Mobula'' (formerly its own genus ''Manta''). The larger species, ''Giant oceanic manta ray, M. birostris'', reaches in width, while the smaller, ''Reef manta ray, 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 Eagle ray, Myliobatidae (eagle rays). They have the largest 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, ... [...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, great hammerhead sharks and manta ray, manta rays are present in the area. 
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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. Tid ... [...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 Estuary, 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, reef, 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 J ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Circumference
In geometry, the circumference () is the perimeter of a circle or ellipse. The circumference is 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 (geometry), locus corresponding to the Edge (geometry), edge of a Disk (geometry), 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 (mathematics), 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 abstrac ... [...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 for Perimeter of an ellipse, its perimeter (also known as circumference), Integral, integration is required to obtain an exact solution. The largest and smallest diameters of an ellipse, also known as its width and height, are typically denoted and . An ellipse has four extreme points: two ''Vertex (geometry), vertices'' at the endpoints of the major axis ... [...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. Some examples of this 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 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Straits
A strait is a water body connecting two seas or water basins. The surface water is, for the most part, at the same elevation on both sides and flows through the strait in both directions, even though the topography generally constricts the flow somewhat. In some straits there is a dominant directional current. Most commonly, the strait is a narrowing channel that lies between two land masses. Straits are loci for sediment accumulation, with sand-size deposits usually occurring on the two strait exits, forming subaqueous fans or deltas. Some straits are not navigable because, for example, they are too narrow or too shallow, or because of an unnavigable reef or archipelago. 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 import ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Motu (geography)
An islet ( ) is generally a small island. Definitions vary, and are not precise, but some suggest that an islet is a very small, often unnamed, island with little or no vegetation to 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 espe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atoll
An atoll () is a ring-shaped island, including a coral rim that encircles a lagoon. There may be coral islands or cays on the rim. Atolls are located in warm tropical or subtropical parts of the oceans and seas where corals can develop. Most of the approximately 440 atolls in the world are in the Pacific Ocean. Two different, well-cited models, the subsidence model and the antecedent karst model, 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 sinking 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 ba ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
