1.
Moon
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The Moon is an astronomical body that orbits planet Earth, being Earths only permanent natural satellite. It is the fifth-largest natural satellite in the Solar System, following Jupiters satellite Io, the Moon is second-densest satellite among those whose densities are known. The average distance of the Moon from the Earth is 384,400 km, the Moon is thought to have formed about 4.51 billion years ago, not long after Earth. It is the second-brightest regularly visible celestial object in Earths sky, after the Sun and its surface is actually dark, although compared to the night sky it appears very bright, with a reflectance just slightly higher than that of worn asphalt. Its prominence in the sky and its cycle of phases have made the Moon an important cultural influence since ancient times on language, calendars, art. The Moons gravitational influence produces the ocean tides, body tides, and this matching of apparent visual size will not continue in the far future. The Moons linear distance from Earth is currently increasing at a rate of 3.82 ±0.07 centimetres per year, since the Apollo 17 mission in 1972, the Moon has been visited only by uncrewed spacecraft. The usual English proper name for Earths natural satellite is the Moon, the noun moon is derived from moone, which developed from mone, which is derived from Old English mōna, which ultimately stems from Proto-Germanic *mǣnōn, like all Germanic language cognates. Occasionally, the name Luna is used, in literature, especially science fiction, Luna is used to distinguish it from other moons, while in poetry, the name has been used to denote personification of our moon. The principal modern English adjective pertaining to the Moon is lunar, a less common adjective is selenic, derived from the Ancient Greek Selene, from which is derived the prefix seleno-. Both the Greek Selene and the Roman goddess Diana were alternatively called Cynthia, the names Luna, Cynthia, and Selene are reflected in terminology for lunar orbits in words such as apolune, pericynthion, and selenocentric. The name Diana is connected to dies meaning day, several mechanisms have been proposed for the Moons formation 4.51 billion years ago, and some 60 million years after the origin of the Solar System. These hypotheses also cannot account for the angular momentum of the Earth–Moon system. This hypothesis, although not perfect, perhaps best explains the evidence, eighteen months prior to an October 1984 conference on lunar origins, Bill Hartmann, Roger Phillips, and Jeff Taylor challenged fellow lunar scientists, You have eighteen months. Go back to your Apollo data, go back to computer, do whatever you have to. Dont come to our conference unless you have something to say about the Moons birth, at the 1984 conference at Kona, Hawaii, the giant impact hypothesis emerged as the most popular. Afterward there were only two groups, the giant impact camp and the agnostics. Giant impacts are thought to have been common in the early Solar System, computer simulations of a giant impact have produced results that are consistent with the mass of the lunar core and the present angular momentum of the Earth–Moon system
2.
Pyramid
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A pyramid is a structure whose outer surfaces are triangular and converge to a single point at the top, making the shape roughly a pyramid in the geometric sense. The base of a pyramid can be trilateral, quadrilateral, or any polygon shape, as such, a pyramid has at least three outer triangular surfaces. The square pyramid, with base and four triangular outer surfaces, is a common version. A pyramids design, with the majority of the closer to the ground. This distribution of weight allowed early civilizations to create stable monumental structures and it has been demonstrated that the common shape of the pyramids of antiquity, from Egypt to Central America, represents the dry-stone construction that requires minimum human work. Pyramids have been built by civilizations in many parts of the world, khufus Pyramid is built mainly of limestone, and is considered an architectural masterpiece. It contains over 2,000,000 blocks ranging in weight from 2.5 tonnes to 15 tonnes and is built on a base with sides measuring about 230 m. Its four sides face the four cardinal points precisely and it has an angle of 52 degrees and it is still the tallest pyramid. The largest pyramid by volume is the Great Pyramid of Cholula, the Mesopotamians built the earliest pyramidal structures, called ziggurats. In ancient times, these were painted in gold/bronze. Since they were constructed of sun-dried mud-brick, little remains of them, ziggurats were built by the Sumerians, Babylonians, Elamites, Akkadians, and Assyrians for local religions. Each ziggurat was part of a complex which included other buildings. The precursors of the ziggurat were raised platforms that date from the Ubaid period during the fourth millennium BC, the earliest ziggurats began near the end of the Early Dynastic Period. The latest Mesopotamian ziggurats date from the 6th century BC, built in receding tiers upon a rectangular, oval, or square platform, the ziggurat was a pyramidal structure with a flat top. Sun-baked bricks made up the core of the ziggurat with facings of fired bricks on the outside, the facings were often glazed in different colors and may have had astrological significance. Kings sometimes had their names engraved on these glazed bricks, the number of tiers ranged from two to seven. It is assumed that they had shrines at the top, but there is no evidence for this. Access to the shrine would have been by a series of ramps on one side of the ziggurat or by a ramp from base to summit
3.
Mexico
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Mexico, officially the United Mexican States, is a federal republic in the southern half of North America. It is bordered to the north by the United States, to the south and west by the Pacific Ocean, to the southeast by Guatemala, Belize, and the Caribbean Sea, and to the east by the Gulf of Mexico. Covering almost two million square kilometers, Mexico is the sixth largest country in the Americas by total area, Mexico is a federation comprising 31 states and a federal district that is also its capital and most populous city. Other metropolises include Guadalajara, Monterrey, Puebla, Toluca, Tijuana, pre-Columbian Mexico was home to many advanced Mesoamerican civilizations, such as the Olmec, Toltec, Teotihuacan, Zapotec, Maya and Aztec before first contact with Europeans. In 1521, the Spanish Empire conquered and colonized the territory from its base in Mexico-Tenochtitlan, Three centuries later, this territory became Mexico following recognition in 1821 after the colonys Mexican War of Independence. The tumultuous post-independence period was characterized by instability and many political changes. The Mexican–American War led to the cession of the extensive northern borderlands, one-third of its territory. The Pastry War, the Franco-Mexican War, a civil war, the dictatorship was overthrown in the Mexican Revolution of 1910, which culminated with the promulgation of the 1917 Constitution and the emergence of the countrys current political system. Mexico has the fifteenth largest nominal GDP and the eleventh largest by purchasing power parity, the Mexican economy is strongly linked to those of its North American Free Trade Agreement partners, especially the United States. Mexico was the first Latin American member of the Organisation for Economic Co-operation and Development and it is classified as an upper-middle income country by the World Bank and a newly industrialized country by several analysts. By 2050, Mexico could become the fifth or seventh largest economy. The country is considered both a power and middle power, and is often identified as an emerging global power. Due to its culture and history, Mexico ranks first in the Americas. Mexico is a country, ranking fourth in the world by biodiversity. In 2015 it was the 9th most visited country in the world, Mexico is a member of the United Nations, the World Trade Organization, the G8+5, the G20, the Uniting for Consensus and the Pacific Alliance. Mēxihco is the Nahuatl term for the heartland of the Aztec Empire, namely, the Valley of Mexico, and its people, the Mexica and this became the future State of Mexico as a division of New Spain prior to independence. It is generally considered to be a toponym for the valley became the primary ethnonym for the Aztec Triple Alliance as a result. After New Spain won independence from Spain, representatives decided to name the new country after its capital and this was founded in 1524 on top of the ancient Mexica capital of Mexico-Tenochtitlan
4.
Pyramid of the Sun
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The Pyramid of the Sun is the largest building in Teotihuacan, believed to have been constructed about 200 CE, and one of the largest in Mesoamerica. The name Pyramid of the Sun comes from the Aztecs, who visited the city of Teotihuacan centuries after it was abandoned and it was constructed in two phases. The first construction stage, around 100 CE, brought the pyramid to nearly the size it is today, the second phase also saw the construction of an altar atop of the pyramid, which has not survived into modern times. Over the structure the ancient Teotihuacanos finished their pyramid with lime plaster imported from surrounding areas, while the pyramid has endured for centuries, the paint and plaster have not and are no longer visible. Jaguar heads and paws, stars, and snake rattles are among the few images associated with the pyramids and it is thought that the pyramid venerated a deity within Teotihuacan society, however, little evidence exists to support this hypothesis. The orientation of the structure may hold some anthropological significance, the day of August 12 is significant because it would have marked the date of the beginning of the present era and the initial day of the Maya long-count calendar. In addition, many important astronomical events can be viewed from the location of the pyramid that are important in terms of agriculture and belief systems of the ancient society. The pyramid was built over a tunnel leading to a cave located six metres down beneath the centre of the structure. Originally this was believed to be a naturally formed lava tube cave and interpreted as possibly the place of Chicomoztoc, more recent excavations have suggested that the space is man-made and could have served as a royal tomb. Only a few caches of artifacts have been found in and around the pyramid and these objects may have represented sacrificial victims. A unique historical artifact discovered near the foot of the pyramid at the end of the century was the Teotihuacan Ocelot. In addition, burial sites of children have found in excavations at the corners of the pyramid. It is believed that these burials were part of a sacrificial ritual dedicating the building of the pyramid, List of Mesoamerican pyramids List of tallest ancient structures
5.
Teotihuacan
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Additionally, Teotihuacan exported fine obsidian tools that garnered high prestige and widespread usage throughout Mesoamerica. The city is thought to have been established around 100 BC, the city may have lasted until sometime between the 7th and 8th centuries AD, but its major monuments were sacked and systematically burned around 550 AD. Teotihuacan began as a new center in the Mexican Highlands around the first century AD. This city came to be the largest and most populated center in the pre-Columbian Americas, Teotihuacan was even home to multi-floor apartment compounds built to accommodate this large population. The term Teotihuacan is also used for the civilization and cultural complex associated with the site. The later Aztecs saw these magnificent ruins and claimed a common ancestry with the Teotihuacanos, the ethnicity of the inhabitants of Teotihuacan is also a subject of debate. Possible candidates are the Nahua, Otomi, or Totonac ethnic groups, scholars have also suggested that Teotihuacan was a multi-ethnic state. The city and the site are located in what is now the San Juan Teotihuacán municipality in the State of México. The site covers a surface area of 83 square kilometres and was designated a UNESCO World Heritage Site in 1987. It is the most visited site in Mexico. The name Teōtīhuacān was given by the Nahuatl-speaking Aztecs centuries after the fall of the city around 550 A. D, the term has been glossed as birthplace of the gods, or place where gods were born, reflecting Nahua creation myths that were said to occur in Teotihuacan. Nahuatl scholar Thelma D. Sullivan interprets the name as place of those who have the road of the gods and this is because the Aztecs believed that the gods created the universe at that site. The name is pronounced in Nahuatl, with the accent on the syllable wa, by normal Nahuatl orthographic conventions, a written accent would not appear in that position. Both this pronunciation and Spanish pronunciation, are used, and both appear in this article. The original name of the city is unknown, but it appears in texts from the Maya region as puh. This naming convention led to confusion in the early 20th century. It now seems clear that Tollan may be understood as a generic Nahua term applied to any large settlement, the early history of Teotihuacan is quite mysterious, and the origin of its founders is uncertain. Around 300 BC, people of the central and southeastern area of Mesoamerica began to gather into larger settlements, Teotihuacan was the largest urban center of Mesoamerica before the Aztecs, almost 1000 years prior to their epoch
6.
Nahuatl
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Nahuatl, known historically as Aztec, is a language or group of languages of the Uto-Aztecan language family. Varieties of Nahuatl are spoken by an estimated 1.5 million Nahua peoples, all Nahuan languages are indigenous to Mesoamerica. Nahuatl has been spoken in central Mexico since at least the seventh century CE and it was the language of the Aztecs who dominated what is now central Mexico during the Late Postclassic period of Mesoamerican history. This early literary language based on the Tenochtitlan variety has been labeled Classical Nahuatl, today, Nahuan languages are spoken in scattered communities, mostly in rural areas throughout central Mexico and along the coastline. There are considerable differences among varieties, and some are mutually unintelligible, Huasteca Nahuatl, with over one million speakers, is the most-spoken variety. They have all been subject to varying degrees of influence from Spanish, No modern Nahuan languages are identical to Classical Nahuatl, but those spoken in and around the Valley of Mexico are generally more closely related to it than those on the periphery. Nahuan languages exhibit a complex morphology characterized by polysynthesis and agglutination, through a very long period of coexistence with the other indigenous Mesoamerican languages, they have absorbed many influences, coming to form part of the Mesoamerican language area. Many words from Nahuatl have been borrowed into Spanish, and since diffused into hundreds of other languages, most of these loanwords denote things indigenous to central Mexico which the Spanish heard mentioned for the first time by their Nahuatl names. English words of Nahuatl origin include avocado, chayote, chili, chocolate, atlatl, coyote, peyote, axolotl, as a language label, the term Nahuatl encompasses a group of closely related languages or divergent dialects within the Nahuan branch of the Uto-Aztecan language family. The Mexican Instituto Nacional de Lenguas Indígenas recognize 30 different individual varieties within the language group labeled Nahuatl, the Ethnologue recognizes 28 varieties with separate ISO codes. Sometimes the label also is used to include the Pipil language of El Salvador, within Mexico the question of whether to consider individual varieties to be languages or dialects of a single language is highly political. This article focuses on describing the history of the group. For details on individual varieties or subgroups, see the individual articles, in the past, the branch of Uto-Aztecan to which Nahuatl belongs has been called Aztecan. From the 1990s onward, the alternative designation Nahuan has been used as a replacement especially in Spanish-language publications. The Nahuan branch of Uto-Aztecan is widely accepted as having two divisions, General Aztec and Pochutec, General Aztec encompasses the Nahuatl and Pipil languages. Pochutec is a scantily attested language, which became extinct in the 20th century, other researchers have argued that Pochutec should be considered a divergent variant of the western periphery. Nahuatl denotes at least Classical Nahuatl together with related languages spoken in Mexico. The inclusion of Pipil into the group is debated, current subclassification of Nahuatl rests on research by Canger, Canger and Lastra de Suárez
7.
Anno Domini
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The terms anno Domini and before Christ are used to label or number years in the Julian and Gregorian calendars. The term anno Domini is Medieval Latin and means in the year of the Lord, There is no year zero in this scheme, so the year AD1 immediately follows the year 1 BC. This dating system was devised in 525 by Dionysius Exiguus of Scythia Minor, the Gregorian calendar is the most widely used calendar in the world today. Traditionally, English followed Latin usage by placing the AD abbreviation before the year number, however, BC is placed after the year number, which also preserves syntactic order. The abbreviation is widely used after the number of a century or millennium. Because BC is the English abbreviation for Before Christ, it is sometimes concluded that AD means After Death. However, this would mean that the approximate 33 years commonly associated with the life of Jesus would not be included in either of the BC, astronomical year numbering and ISO8601 avoid words or abbreviations related to Christianity, but use the same numbers for AD years. The Anno Domini dating system was devised in 525 by Dionysius Exiguus to enumerate the years in his Easter table. His system was to replace the Diocletian era that had used in an old Easter table because he did not wish to continue the memory of a tyrant who persecuted Christians. The last year of the old table, Diocletian 247, was followed by the first year of his table. Thus Dionysius implied that Jesus Incarnation occurred 525 years earlier, without stating the year during which his birth or conception occurred. Blackburn & Holford-Strevens briefly present arguments for 2 BC,1 BC, There were inaccuracies in the list of consuls There were confused summations of emperors regnal years It is not known how Dionysius established the year of Jesuss birth. It is convenient to initiate a calendar not from the day of an event. For example, the Islamic calendar begins not from the date of the Hegira, at the time, it was believed by some that the Resurrection and end of the world would occur 500 years after the birth of Jesus. The old Anno Mundi calendar theoretically commenced with the creation of the based on information in the Old Testament. It was believed that, based on the Anno Mundi calendar, Anno Mundi 6000 was thus equated with the resurrection and the end of the world but this date had already passed in the time of Dionysius. The Anglo-Saxon historian the Venerable Bede, who was familiar with the work of Dionysius Exiguus, used Anno Domini dating in his Ecclesiastical History of the English People, completed in 731. e. On the continent of Europe, Anno Domini was introduced as the era of choice of the Carolingian Renaissance by the English cleric and scholar Alcuin in the late eighth century
8.
Symmetry in biology
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Symmetry in biology is the balanced distribution of duplicate body parts or shapes within the body of an organism. In nature and biology, symmetry is always approximate, for example plant leaves, while considered symmetrical, symmetry creates a class of patterns in nature, where the near-repetition of the pattern element is by reflection or rotation. The body plans of most multicellular organisms exhibit some form of symmetry, whether radial, bilateral, a small minority, notably among the sponges, exhibit no symmetry. Radially symmetric organisms resemble a pie where several cutting planes produce roughly identical pieces, such an organism exhibits no left or right sides. They have a top and a surface only. Most radially symmetric animals are symmetrical about an axis extending from the center of the oral surface, radial symmetry is especially suitable for sessile animals such as the sea anemone, floating animals such as jellyfish, and slow moving organisms such as starfish. Animals in the phyla cnidaria and echinodermata are radially symmetric, although many sea anemones and some corals have bilateral symmetry defined by a single structure, many flowers are radially symmetric or actinomorphic. Roughly identical flower parts – petals, sepals, and stamens occur at intervals around the axis of the flower. Many viruses have radial symmetries, their coats being composed of a small number of protein molecules arranged in a regular pattern to form polyhedrons, spheres. Tetramerism is a variant of radial symmetry found in jellyfish, which have four canals in an otherwise radial body plan, pentamerism, another variant of radial symmetry, means the organism is in five parts around a central axis, 72° apart. Among animals, only the echinoderms such as sea stars, sea urchins, being bilaterian animals, however, they initially develop with mirror symmetry as larvae, then gain pentaradial symmetry later. Flowering plants show fivefold symmetry in many flowers and in various fruits and this is well seen in the arrangement of the five carpels in an apple cut transversely. Hexamerism is found in the corals and sea anemones which are divided into two based on their symmetry. The most common corals in the subclass Hexacorallia have a body plan, their polyps have sixfold internal symmetry. Octamerism is found in corals of the subclass Octocorallia and these have polyps with eight tentacles and octameric radial symmetry. The octopus, however, has symmetry, despite its eight arms. Spherical symmetry occurs in an if it is able to be cut into two identical halves through any cut that runs through the organisms center. Organisms which show approximate spherical symmetry include the green alga Volvox
9.
Great Goddess of Teotihuacan
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The Great Goddess of Teotihuacan is a proposed goddess of the pre-Columbian Teotihuacan civilization, in what is now Mexico. In years leading up to 1942, a series of murals were found in the Tepantitla compound in Teotihuacan, the Tepantitla compound provided housing for what appears to have been high status citizens and its walls are adorned with brightly painted frescoes. The largest figures within the murals depicted complex and ornate deities or supernaturals, in 1942, archaeologist Alfonso Caso identified these central figures as a Teotihuacan equivalent of Tlaloc, the Mesoamerican god of rain and warfare. This was the view for some 30 years. In 1974, Peter Furst suggested that the murals instead showed a feminine deity and their analysis of the murals was based on a number of factors including the gender of accompanying figures, the green bird in the headdress, and the spiders seen above the figure. Pasztory concluded that the figures represented a vegetation and fertility goddess that was a predecessor of the much later Aztec goddess Xochiquetzal, in 1983, Karl Taube termed this goddess the Teotihuacan Spider Woman. The more neutral description of this deity as the Great Goddess has since gained currency, the 3-metre-high blocky statue which formerly sat near the base of the Pyramid of Moon is thought to represent the Great Goddess, despite the absence of the bird-headdress or the fanged nosepiece. Esther Pasztory speculates that the Great Goddess, as a distant and ambivalent mother figure, was able to provide a structure for Teotihuacan that transcended divisions within the city. The Great Goddess is apparently peculiar to Teotihuacan, and does not appear outside the city except where Teotihuacanos settled. There is very little trace of the Great Goddess in the Valley of Mexicos later Toltec culture, although an earth goddess image has been identified on Stela 1, from Xochicalco, a Toltec contemporary. The wresting of this aspect from the Great Goddess was memorialized in the myth Huitzilopochtli, berlo also sees echoes of the Great Goddess in the veneration of the Virgin of Guadalupe. Two major defining characteristics of the Great Goddess are a bird headress, the outer fangs curl away from the center, while the middle fang points down. Other defining characteristics include the red and yellow, note that the Goddess appears with a yellowish cast in both murals. In the depiction from the Tepantitla compound, the Great Goddess appears with vegetation growing out of her head, spiders and butterflies appear on the vegetation and water drips from its branches and flows from the hands of the Great Goddess. Water also flows from her lower body and these many representations of water led Caso to declare this to be a representation of the rain god, Tlaloc. Several of these figures are swimming in the rivers flowing from a mountain at the bottom of the scene. The Great Goddess is thought to have been a goddess of the underworld, darkness, the earth, water, war, and possibly even creation itself. To the ancient civilizations of Mesoamerica, the jaguar, the owl, the fact that the Great Goddess is frequently depicted with all of these creatures further supports the idea of her underworld connections
