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84 (number)
84 (eighty-four) is the natural number following 83 and preceding 85. In mathematics 84 is: * the sum of the first seven triangular numbers (making it a tetrahedral number). * a Dodecahedral number. * the sum of a twin prime (41 + 43). * a semiperfect number, being thrice a perfect number. * a palindromic number and a repdigit in bases 11 (7711), 13 (6613), 20 (4420), 27 (3327), and 41 (2241). * the lim sup of the largest finite subgroup of the mapping class group of a genus ''g'' surface divided by ''g''. A hepteract is a seven-dimensional hypercube with 84 penteract 5-faces. In astronomy *Messier object M84, a magnitude 11.0 lenticular galaxy in the constellation Virgo *The New General Cataloguebr>object NGC 84, a single star in the constellation Andromeda In other fields Eighty-four is also: * The year AD 84, 84 BC, or 1984. * The number of years in the , a cycle used in the past by Celtic peoples, equal to 3 cycles of the Julian Calendar and to 4 Metonic ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural Number
In mathematics, the natural numbers are those numbers used for counting (as in "there are ''six'' coins on the table") and ordering (as in "this is the ''third'' largest city in the country"). Numbers used for counting are called ''Cardinal number, cardinal numbers'', and numbers used for ordering are called ''Ordinal number, ordinal numbers''. Natural numbers are sometimes used as labels, known as ''nominal numbers'', having none of the properties of numbers in a mathematical sense (e.g. sports Number (sports), jersey numbers). Some definitions, including the standard ISO/IEC 80000, ISO 80000-2, begin the natural numbers with , corresponding to the non-negative integers , whereas others start with , corresponding to the positive integers Texts that exclude zero from the natural numbers sometimes refer to the natural numbers together with zero as the whole numbers, while in other writings, that term is used instead for the integers (including negative integers). The natural ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Penteract
In five-dimensional geometry, a 5-cube is a name for a five-dimensional hypercube with 32 vertices, 80 edges, 80 square faces, 40 cubic cells, and 10 tesseract 4-faces. It is represented by Schläfli symbol or , constructed as 3 tesseracts, , around each cubic ridge. It can be called a penteract, a portmanteau of the Greek word , for 'five' (dimensions), and the word ''tesseract'' (the 4-cube). It can also be called a regular deca-5-tope or decateron, being a 5-dimensional polytope constructed from 10 regular facets. Related polytopes It is a part of an infinite hypercube family. The dual of a 5-cube is the 5-orthoplex, of the infinite family of orthoplexes. Applying an '' alternation'' operation, deleting alternating vertices of the 5-cube, creates another uniform 5-polytope, called a 5-demicube, which is also part of an infinite family called the demihypercubes. The 5-cube can be seen as an ''order-3 tesseractic honeycomb'' on a 4-sphere. It is related to the Euclidean 4- ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Insular Latercus
Insular is an adjective used to describe: * An island * Someone who is isolated and parochial Insular may also refer to: Sub-national territories or regions * Insular Chile * Insular region of Colombia * Insular Ecuador, administratively known as Galápagos Province * Insular Region (Equatorial Guinea) * Insular Italy * Insular Portugal, comprises the Madeira and Azores Autonomous Regions * Insular Southeast Asia * Insular areas of the United States ** Insular Cases, a series of U.S. Supreme Court decisions in 1901, about the status of U.S. territories acquired in the Spanish–American War ** Bureau of Insular Affairs, a unit of the U.S. government's War Department which administered certain insular areas from 1902 to 1939 ** Office of Insular Affairs, a unit of the U.S. Department of the Interior that oversees federal administration of several insular areas (and the successor to the Bureau of Insular Affairs). ** Insular Government of the Philippine Islands, the U.S. territori ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
1984
Events January * January 1 – The Bornean Sultanate of Brunei gains full independence from the United Kingdom, having become a British protectorate in 1888. * January 7 – Brunei becomes the sixth member of the Association of Southeast Asian Nations (ASEAN). * January 10 ** The United States and the Vatican (Holy See) restore full diplomatic relations. ** The Victoria Agreement is signed, institutionalising the Indian Ocean Commission. *January 24 – Steve Jobs launches the Macintosh personal computer in the United States. February * February 3 ** Dr. John Buster and the research team at Harbor–UCLA Medical Center announce history's first embryo transfer from one woman to another, resulting in a live birth. ** STS-41-B: Space Shuttle ''Challenger'' is launched on the 10th Space Shuttle mission. * February 7 – Astronauts Bruce McCandless II and Robert L. Stewart make the first untethered space walk. * February 8– 19 – The 1984 Winter Olympics are held in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
84 BC
__NOTOC__ Year 84 BC was a year of the pre-Julian Roman calendar. At the time it was known as the Year of the Consulship of Carbo and Cinna (or, less frequently, year 670 ''Ab urbe condita''). The denomination 84 BC for this year has been used since the early medieval period, when the Anno Domini calendar era became the prevalent method in Europe for naming years. Events By place Asia * Battle of Cana: The Arab Nabataean Kingdom decisively defeats the Greek Seleucid Empire, slaying King Antiochus XII Dionysus, at modern-day Umm Qais in Jordan. Roman Republic * The First Mithridatic War comes to an end. Births * Catullus, Roman poet (approximate date) (d. c. 54 BC) * Servilius Casca, Roman politician (d. c. 42 BC) * Surena, Parthian general (d. 53 BC) Deaths * Apellicon of Teos, Greek book collector (approximate date) * Gaius Flavius Fimbria, Roman politician and general * Lucius Cornelius Cinna, Roman consul A consul held the highest elected political off ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Vietnam In Its Region
Vietnam or Viet Nam ( vi, Việt Nam, ), officially the Socialist Republic of Vietnam,., group="n" is a country in Southeast Asia, at the eastern edge of mainland Southeast Asia, with an area of and population of 96 million, making it the world's List of countries and dependencies by population, sixteenth-most populous country. Vietnam borders China to the north, and Laos and Cambodia to the west. It shares Maritime boundary, maritime borders with Thailand through the Gulf of Thailand, and the Philippines, Indonesia, and Malaysia through the South China Sea. Its capital is Hanoi and its largest city is Ho Chi Minh City (commonly known as Saigon). Vietnam was inhabited by the Paleolithic age, with states established in the first millennium BC on the Red River Delta in modern-day northern Vietnam. The Han dynasty annexed Northern and Central Vietnam under Vietnam under Chinese rule, Chinese rule from 111 BC, until the Ngô dynasty, first dynasty emerged in 939. Successiv ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Andromeda (constellation)
Andromeda is one of the 48 constellations listed by the 2nd-century Greco-Roman astronomer Ptolemy, and one of the 88 modern constellations. Located in the northern celestial hemisphere, it is named for Andromeda, daughter of Cassiopeia, in the Greek myth, who was chained to a rock to be eaten by the sea monster Cetus. Andromeda is most prominent during autumn evenings in the Northern Hemisphere, along with several other constellations named for characters in the Perseus myth. Because of its northern declination, Andromeda is visible only north of 40° south latitude; for observers farther south, it lies below the horizon. It is one of the largest constellations, with an area of 722 square degrees. This is over 1,400 times the size of the full moon, 55% of the size of the largest constellation, Hydra, and over 10 times the size of the smallest constellation, Crux. Its brightest star, Alpha Andromedae, is a binary star that has also been counted as a part of Pegasus, while ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
NGC 84
NGC 84 (PGC 3325897) is a star in the Andromeda constellation. It was recorded on November 14, 1884 by Guillaume Bigourdan. It is situated close to the Celestial equator, making it at least partly visible in the sky, from both hemispheres in certain times of the year. It is usually mistaken with PGC 1384. NGC 84 is displayed as PGC 1384 in Wikisky Sky-Map.org (or WikiSky.org) is a wiki and interactive sky map that covers more than half a billion celestial objects. Users can view the whole star sky at once and zoom in to view areas in greater detail. WikiSky includes many stars, galaxies, .... References External links * 0084 18841114 Discoveries by Guillaume Bigourdan Andromeda (constellation) {{star-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
New General Catalogue
The ''New General Catalogue of Nebulae and Clusters of Stars'' (abbreviated NGC) is an astronomical catalogue of deep-sky objects compiled by John Louis Emil Dreyer in 1888. The NGC contains 7,840 objects, including galaxies, star clusters and emission nebulae. Dreyer published two supplements to the NGC in 1895 and 1908, known as the ''Index Catalogues'' (abbreviated IC), describing a further 5,386 astronomical objects. Thousands of these objects are best known by their NGC or IC numbers, which remain in widespread use. The NGC expanded and consolidated the cataloguing work of William and Caroline Herschel, and John Herschel's ''General Catalogue of Nebulae and Clusters of Stars''. Objects south of the celestial equator are catalogued somewhat less thoroughly, but many were included based on observation by John Herschel or James Dunlop. The NGC contained multiple errors, but attempts to eliminate them were made by the ''Revised New General Catalogue'' (RNGC) by Jack W. Sulent ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Virgo (constellation)
Virgo is one of the constellations of the zodiac. Its name is Latin for maiden, and its old astronomical symbol is (♍︎). Lying between Leo (constellation), Leo to the west and Libra (constellation), Libra to the east, it is the second-largest constellation in the sky (after Hydra (constellation), Hydra) and the largest constellation in the zodiac. The ecliptic intersects the celestial equator within this constellation and Pisces (constellation), Pisces. Underlying these technical two definitions, the sun passes directly overhead of the equator, within this constellation, at the September equinox. Virgo can be easily found through its brightest star, Spica. Location Virgo is prominent in the spring sky in the Northern Hemisphere, visible all night in March and April. As the largest zodiac constellation, the Sun takes 44 days to pass through it, longer than any other. From 1990 and until 2062, this will take place from September 16 to October 30. It is located in the third ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Constellation
A constellation is an area on the celestial sphere in which a group of visible stars forms Asterism (astronomy), a perceived pattern or outline, typically representing an animal, mythological subject, or inanimate object. The origins of the earliest constellations likely go back to prehistory. People used them to relate stories of their beliefs, experiences, creation myth, creation, or mythology. Different cultures and countries adopted their own constellations, some of which lasted into the early 20th century before today's constellations were internationally recognized. The recognition of constellations has changed significantly over time. Many changed in size or shape. Some became popular, only to drop into obscurity. Some were limited to a single culture or nation. The 48 traditional Western constellations are Greek. They are given in Aratus' work ''Phenomena'' and Ptolemy's ''Almagest'', though their origin probably predates these works by several centuries. Constellation ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lenticular Galaxy
A lenticular galaxy (denoted S0) is a type of galaxy intermediate between an elliptical (denoted E) and a spiral galaxy in galaxy morphological classification schemes. It contains a large-scale disc but does not have large-scale spiral arms. Lenticular galaxies are disc galaxies that have used up or lost most of their interstellar matter and therefore have very little ongoing star formation. They may, however, retain significant dust in their disks. As a result, they consist mainly of aging stars (like elliptical galaxies). Despite the morphological differences, lenticular and elliptical galaxies share common properties like spectral features and scaling relations. Both can be considered early-type galaxies that are passively evolving, at least in the local part of the Universe. Connecting the E galaxies with the S0 galaxies are the ES galaxies with intermediate-scale discs. Morphology and structure Classification Lenticular galaxies are unique in that they have a visibl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
