1.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
2.
Apollo 17
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Apollo 17 was the final mission of NASAs Apollo program, the enterprise that landed the first humans on the Moon. Apollo 17 was the first night launch of a U. S. human spaceflight and it was a J-type mission which included three days on the lunar surface, extended scientific capability, and the third Lunar Roving Vehicle. Evans took scientific measurements and photographs from orbit using a Scientific Instruments Module mounted in the Service Module, Cernan, Evans and Schmitt returned to Earth on December 19 after a 12-day mission. Apollo 17 is the most recent manned Moon landing and was the last time humans travelled beyond low Earth orbit, the mission broke several records, the longest moon landing, longest total extravehicular activities, largest lunar sample, and longest time in lunar orbit. Eugene Cernan, Ronald Evans, and former X-15 pilot Joe Engle were assigned to the crew of Apollo 14. Engle flew sixteen X-15 flights, three of which exceeded the 50 mi border of space, following the rotation pattern that a backup crew would fly as the prime crew three missions later, Cernan, Evans, and Engle would have flown Apollo 17. Harrison Schmitt served on the crew of Apollo 15 and. However, Apollo 18 was cancelled in September 1970, following this decision, the scientific community pressured NASA to assign a geologist to an Apollo landing, as opposed to a pilot trained in geology. In light of pressure, Harrison Schmitt, a professional geologist, was assigned the Lunar Module Pilot position on Apollo 17. Scientist-astronaut Curt Michel believed that it was his own decision to resign, after it became clear that he would not be given a flight assignment, that mobilized this action. Subsequent to the decision to assign Schmitt to Apollo 17, there remained the question of which crew would become prime crew of the mission. NASA Director of Flight Crew Operations Deke Slayton ultimately assigned the crew of Apollo 14, along with Schmitt. The Apollo 15 prime crew received the backup assignment since this was to be the last lunar mission, however, when the Apollo 15 postage stamp incident became public in early 1972 the crew was reprimanded by NASA and the United States Air Force. Robert F. Overmyer Robert A. Parker C, three white stars above the red bars represent the three crewmen of the mission. The background includes the Moon, the planet Saturn and a galaxy or nebula, the wing of the eagle partially overlays the Moon, suggesting mans established presence there. The gaze of Apollo and the direction of the eagles motion embody mans intention to further destinations in space. The patch includes, along with the colors of the U. S. flag, the image of Apollo in the mission insignia is a rendering of the Apollo Belvedere sculpture. The insignia was designed by Robert McCall, with input from the crew, since Apollo 17 was to be the final lunar landing of the Apollo program, high-priority landing sites that had not been visited previously were given consideration for potential exploration
3.
World map
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A world map is a map of most or all of the surface of the Earth. World maps form a category of maps due to the problem of projection. Maps by necessity distort the presentation of the earths surface and these distortions reach extremes in a world map. The many ways of projecting the earth reflect diverse technical and aesthetic goals for world maps, World maps are also distinct for the global knowledge required to construct them. A meaningful map of the world could not be constructed before the European Renaissance because less than half of the earths coastlines, new knowledge of the earths surface has been accumulating ever since and continues to this day. Maps of the world generally focus either on political features or on physical features, political maps emphasize territorial boundaries and human settlement. Physical maps show geographic features such as mountains, soil type or land use, geological maps show not only the surface, but characteristics of the underlying rock, fault lines, and subsurface structures. Choropleth maps use color hue and intensity to contrast differences between regions, such as demographic or economic statistics, a map is made using a map projection, which is any method of representing a globe on a plane. All projections distort distances and directions, and each projection distributes those distortions differently, perhaps the most well known projection is the Mercator Projection, originally designed as a nautical chart. A thematic map shows geographic information about one or a few focused subjects and these maps can portray physical, social, political, cultural, economic, sociological, agricultural, or any other aspects of a city, state, region, nation, or continent. Early world maps cover depictions of the world from the Iron Age to the Age of Discovery, old maps provide much information about what was known in times past, as well as the philosophy and cultural basis of the map, which were often much different from modern cartography. Maps are one means by which scientists distribute their ideas and pass them on to future generations, the World Map, 1300–1492, The Persistence of Tradition and Transformation. ISBN1421404303 Harvey, P. D. A, the Hereford world map, medieval world maps and their context
4.
Life
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Various forms of life exist, such as plants, animals, fungi, protists, archaea, and bacteria. The criteria can at times be ambiguous and may or may not define viruses, viroids, biology is the primary science concerned with the study of life, although many other sciences are involved. The definition of life is controversial, the current definition is that organisms maintain homeostasis, are composed of cells, undergo metabolism, can grow, adapt to their environment, respond to stimuli, and reproduce. However, many other definitions have been proposed, and there are some borderline cases. Modern definitions are more complex, with input from a diversity of scientific disciplines, biophysicists have proposed many definitions based on chemical systems, there are also some living systems theories, such as the Gaia hypothesis, the idea that the Earth itself is alive. Another theory is that life is the property of systems, and yet another is elaborated in complex systems biology. Abiogenesis describes the process of life arising from non-living matter. Properties common to all organisms include the need for certain chemical elements to sustain biochemical functions. Life on Earth first appeared as early as 4.28 billion years ago, soon after ocean formation 4.41 billion years ago, Earths current life may have descended from an RNA world, although RNA-based life may not have been the first. The mechanism by which began on Earth is unknown, though many hypotheses have been formulated and are often based on the Miller–Urey experiment. The earliest known forms are microfossils of bacteria. In July 2016, scientists reported identifying a set of 355 genes believed to be present in the last universal ancestor of all living organisms. Since its primordial beginnings, life on Earth has changed its environment on a time scale. To survive in most ecosystems, life must often adapt to a range of conditions. Some microorganisms, called extremophiles, thrive in physically or geochemically extreme environments that are detrimental to most other life on Earth, Aristotle was the first person to classify organisms. Later, Carl Linnaeus introduced his system of nomenclature for the classification of species. Eventually new groups and categories of life were discovered, such as cells and microorganisms, cells are sometimes considered the smallest units and building blocks of life. There are two kinds of cells, prokaryotic and eukaryotic, both of which consist of cytoplasm enclosed within a membrane and contain many such as proteins
5.
Civilization
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Historically, a civilization was a so-called advanced culture in contrast to more supposedly primitive cultures. As an uncountable noun, civilization also refers to the process of a society developing into a centralized, urbanized, stratified structure, Civilization concentrates power, extending human control over the rest of nature, including over other human beings. The earlier neolithic technology and lifestyle was established first in the Middle East, and later in the Yangtze and Yellow River basins in China, similar pre-civilized neolithic revolutions also began independently from 7,000 BCE in such places as northwestern South America and Mesoamerica. These were among the six civilizations worldwide that arose independently, Mesopotamia is the site of the earliest developments of the Neolithic Revolution from around 10,000 BCE, with civilizations developing from 6,500 years ago. Towards the end of the Neolithic period, various elitist Chalcolithic civilizations began to rise in various cradles from around 3300 BCE. Chalcolithic civilizations, as defined above, also developed in Pre-Columbian Americas and, despite an early start in Egypt, Axum and Kush, the English word civilization comes from the 16th-century French civilisé, from Latin civilis, related to civis and civitas. The fundamental treatise is Norbert Eliass The Civilizing Process, which traces social mores from medieval courtly society to the Early Modern period, in The Philosophy of Civilization, Albert Schweitzer outlines two opinions, one purely material and the other material and ethical. Adjectives like civility developed in the mid-16th century, the abstract noun civilization, meaning civilized condition, came in the 1760s, again from French. The word was therefore opposed to barbarism or rudeness, in the pursuit of progress characteristic of the Age of Enlightenment. In the late 1700s and early 1800s, during the French revolution, civilization was used in the singular, never in the plural and this is still the case in French. The use of civilizations as a noun was in occasional use in the 19th century. Only in this sense does it become possible to speak of a medieval civilization. Already in the 18th century, civilization was not always seen as an improvement, one historically important distinction between culture and civilization is from the writings of Rousseau, particularly his work about education, Emile. From this, a new approach was developed, especially in Germany, first by Johann Gottfried Herder and this sees cultures as natural organisms, not defined by conscious, rational, deliberative acts, but a kind of pre-rational folk spirit. Civilization, in contrast, though more rational and more successful in material progress, is unnatural and leads to vices of social life such as guile, hypocrisy, envy and avarice. In World War II, Leo Strauss, having fled Germany, argued in New York that this opinion of civilization was behind Nazism, Social scientists such as V. Gordon Childe have named a number of traits that distinguish a civilization from other kinds of society. Andrew Nikiforuk argues that civilizations relied on shackled human muscle and it took the energy of slaves to plant crops, clothe emperors, and build cities and considers slavery to be a common feature of pre-modern civilizations. All civilizations have depended on agriculture for subsistence, grain farms can result in accumulated storage and a surplus of food, particularly when people use intensive agricultural techniques such as artificial fertilization, irrigation and crop rotation
6.
History of the world
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The history of the world describes the history of humanity as determined by the study of archaeological and written records, beginning with the invention of writing. The latter period marked a change in history, as humans began the systematic husbandry of plants. Agriculture advanced, and most humans transitioned from a nomadic to a lifestyle as farmers in permanent settlements. As farming developed, grain agriculture became more sophisticated and prompted a division of labour to store food between growing seasons, labour divisions then led to the rise of a leisured upper class and the development of cities. The growing complexity of human societies necessitated systems of writing and accounting, in the mid-15th century, the invention of modern printing, employing movable type, revolutionized communication, helping end the Middle Ages and ushering in the Scientific Revolution. By the 18th century, the accumulation of knowledge and technology, outside the Old World, including ancient China and ancient India, historical timelines unfolded differently. However, by the 18th century, due to world trade and colonization. Genetic measurements indicate that the ape lineage which would lead to Homo sapiens diverged from the lineage that would lead to chimpanzees around six years ago. It is thought that the Australopithecine genus, which were likely the first apes to walk upright, anatomically modern humans arose in Africa about 200,000 years ago, and reached behavioural modernity about 50,000 years ago. Modern humans spread rapidly from Africa into the frost-free zones of Europe, the rapid expansion of humankind to North America and Oceania took place at the climax of the most recent ice age, when temperate regions of today were extremely inhospitable. Yet, humans had colonized nearly all the parts of the globe by the end of the Ice Age. Other hominids such as Homo erectus had been using simple wood and stone tools for millennia, at some point, humans began using fire for heat and cooking. They also developed language in the Palaeolithic period and a repertoire that included systematic burial of the dead. Early artistic expression can be found in the form of paintings and sculptures made from wood and bone, showing a spirituality generally interpreted as animism. During this period, all lived as hunter-gatherers, and were generally nomadic. The Neolithic Revolution, beginning about 8,000 BCE, saw the development of agriculture, Mesopotamia is the site of the earliest developments of the Neolithic Revolution. Farming permitted far denser populations, which in time organized into states, agriculture also created food surpluses that could support people not directly engaged in food production. The development of agriculture permitted the creation of the first cities and these were centres of trade, manufacturing and political power with nearly no agricultural production of their own
7.
World population
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In demographics, the world population is the total number of humans currently living. As of March 2017, it was estimated at 7.49 billion, the United Nations estimates it will further increase to 11.2 billion in the year 2100. World population has experienced growth since the end of the Great Famine of 1315–17 and the Black Death in 1350. The highest population growth rates – global population increases above 1. 8% per year – occurred between 1955-1975 peaking to 2. 06% between 1965-1970, the growth rate has declined to 1. 18% between 2010-2015 and is projected to decline to 0. 13% by the year 2100. World population reached 7 billion on October 31,2011 according to the United Nations Population Fund, and on March 12,2012 according to the United States Census Bureau. The median age of the population was estimated to be 30.1 years in 2016, with the male median age estimated to be 29.4 years. 2003 UN Population Division population projections for the year 2150 range between 3.2 and 24.8 billion. One of many independent mathematical models supports the estimate, while a 2014 estimate forecasts between 9.3 and 12.6 billion in 2100, and continued growth thereafter. Some analysts have questioned the sustainability of further population growth, highlighting the growing pressures on the environment, global food supplies. Estimates on the number of humans who have ever lived range in the order of 106 to 108 billion. Six of the Earths seven continents are permanently inhabited on a large scale, Asia is the most populous continent, with its 4.3 billion inhabitants accounting for 60% of the world population. The worlds two most populated countries alone, China and India, together constitute about 37% of the worlds population, Africa is the second most populated continent, with around 1 billion people, or 15% of the worlds population. Europes 733 million people make up 12% of the population as of 2012. Northern America, primarily consisting of the United States, Mexico, and Canada, has a population of around 352 million, and Oceania, the least-populated region, has about 35 million inhabitants. Though it is not permanently inhabited by any fixed population, Antarctica has a small, fluctuating international population and this population tends to rise in the summer months and decrease significantly in winter, as visiting researchers return to their home countries. Estimates of world population by their nature are an aspect of modernity, more refined estimates, broken down by continents, were published in the first half of the 19th century, at 600 to 1000 million in the early 1800s and at 800 to 1000 million in the 1840s. Estimates of the population of the world at the time agriculture emerged in around 10,000 BCE have ranged between 1 million and 15 million. Even earlier, genetic evidence suggests humans may have gone through a bottleneck of between 1,000 and 10,000 people about 70,000 BCE, according to the Toba catastrophe theory
8.
Old English
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Old English or Anglo-Saxon is the earliest historical form of the English language, spoken in England and southern and eastern Scotland in the early Middle Ages. It was brought to Great Britain by Anglo-Saxon settlers probably in the mid 5th century, Old English developed from a set of Anglo-Frisian or North Sea Germanic dialects originally spoken by Germanic tribes traditionally known as the Angles, Saxons, and Jutes. As the Anglo-Saxons became dominant in England, their language replaced the languages of Roman Britain, Common Brittonic, a Celtic language, Old English had four main dialects, associated with particular Anglo-Saxon kingdoms, Mercian, Northumbrian, Kentish and West Saxon. It was West Saxon that formed the basis for the standard of the later Old English period, although the dominant forms of Middle. The speech of eastern and northern parts of England was subject to strong Old Norse influence due to Scandinavian rule, Old English is one of the West Germanic languages, and its closest relatives are Old Frisian and Old Saxon. Like other old Germanic languages, it is different from Modern English. Old English grammar is similar to that of modern German, nouns, adjectives, pronouns, and verbs have many inflectional endings and forms. The oldest Old English inscriptions were using a runic system. Old English was not static, and its usage covered a period of 700 years, from the Anglo-Saxon settlement of Britain in the 5th century to the late 11th century, some time after the Norman invasion. While indicating that the establishment of dates is a process, Albert Baugh dates Old English from 450 to 1150, a period of full inflections. Perhaps around 85 per cent of Old English words are no longer in use, Old English is a West Germanic language, developing out of Ingvaeonic dialects from the 5th century. It came to be spoken over most of the territory of the Anglo-Saxon kingdoms which became the Kingdom of England and this included most of present-day England, as well as part of what is now southeastern Scotland, which for several centuries belonged to the Anglo-Saxon kingdom of Northumbria. Other parts of the island – Wales and most of Scotland – continued to use Celtic languages, Norse was also widely spoken in the parts of England which fell under Danish law. Anglo-Saxon literacy developed after Christianisation in the late 7th century, the oldest surviving text of Old English literature is Cædmons Hymn, composed between 658 and 680. There is a corpus of runic inscriptions from the 5th to 7th centuries. The Old English Latin alphabet was introduced around the 9th century, with the unification of the Anglo-Saxon kingdoms by Alfred the Great in the later 9th century, the language of government and literature became standardised around the West Saxon dialect. In Old English, typical of the development of literature, poetry arose before prose, a later literary standard, dating from the later 10th century, arose under the influence of Bishop Æthelwold of Winchester, and was followed by such writers as the prolific Ælfric of Eynsham. This form of the language is known as the Winchester standard and it is considered to represent the classical form of Old English
9.
Creation myth
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A creation myth is a symbolic narrative of how the world began and how people first came to inhabit it. While in popular usage the term often refers to false or fanciful stories, formally. Cultures generally regard their creation myths as true, in the society in which it is told, a creation myth is usually regarded as conveying profound truths, metaphorically, symbolically and sometimes in a historical or literal sense. They are commonly, although not always, considered cosmogonical myths – that is, Creation myths often share a number of features. They often are considered sacred accounts and can be found in all known religious traditions. They are all stories with a plot and characters who are either deities, human-like figures, or animals and they are often set in a dim and nonspecific past that historian of religion Mircea Eliade termed in illo tempore. Creation myths develop in oral traditions and therefore typically have multiple versions, found throughout human culture, Creation myth definitions from modern references, A symbolic narrative of the beginning of the world as understood in a particular tradition and community. Creation myths are of importance for the valuation of the world, for the orientation of humans in the universe. Creation myths tell us how things began, all cultures have creation myths, they are our primary myths, the first stage in what might be called the psychic life of the species. As cultures, we identify ourselves through the collective dreams we call creation myths, … Creation myths explain in metaphorical terms our sense of who we are in the context of the world, and in so doing they reveal our real priorities, as well as our real prejudices. Our images of creation say a deal about who we are. A philosophical and theological elaboration of the myth of creation within a religious community. Religion professor Mircea Eliade defined the word myth in terms of creation, Myth narrates a history, it relates an event that took place in primordial Time. All creation myths are in one sense etiological because they attempt to explain how the world was formed, in the past historians of religion and other students of myth thought of them as forms of primitive or early-stage science or religion and analyzed them in a literal or logical sense. However they are seen as symbolic narratives which must be understood in terms of their own cultural context. Charles Long writes, The beings referred to in the myth – gods, animals, the myths should not be understood as attempts to work out a rational explanation of deity. While creation myths are not literal explications they do serve to define an orientation of humanity in the world in terms of a birth story. They are the basis of a worldview that reaffirms and guides how people relate to the world, to any assumed spiritual world
10.
Planet
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The term planet is ancient, with ties to history, astrology, science, mythology, and religion. Several planets in the Solar System can be seen with the naked eye and these were regarded by many early cultures as divine, or as emissaries of deities. As scientific knowledge advanced, human perception of the planets changed, in 2006, the International Astronomical Union officially adopted a resolution defining planets within the Solar System. This definition is controversial because it excludes many objects of mass based on where or what they orbit. The planets were thought by Ptolemy to orbit Earth in deferent, at about the same time, by careful analysis of pre-telescopic observation data collected by Tycho Brahe, Johannes Kepler found the planets orbits were not circular but elliptical. As observational tools improved, astronomers saw that, like Earth, the planets rotated around tilted axes, and some shared such features as ice caps and seasons. Since the dawn of the Space Age, close observation by space probes has found that Earth and the planets share characteristics such as volcanism, hurricanes, tectonics. Planets are generally divided into two types, large low-density giant planets, and smaller rocky terrestrials. Under IAU definitions, there are eight planets in the Solar System, in order of increasing distance from the Sun, they are the four terrestrials, Mercury, Venus, Earth, and Mars, then the four giant planets, Jupiter, Saturn, Uranus, and Neptune. Six of the planets are orbited by one or more natural satellites, several thousands of planets around other stars have been discovered in the Milky Way. e. in the habitable zone. On December 20,2011, the Kepler Space Telescope team reported the discovery of the first Earth-sized extrasolar planets, Kepler-20e and Kepler-20f, orbiting a Sun-like star, Kepler-20. A2012 study, analyzing gravitational microlensing data, estimates an average of at least 1.6 bound planets for every star in the Milky Way, around one in five Sun-like stars is thought to have an Earth-sized planet in its habitable zone. The idea of planets has evolved over its history, from the lights of antiquity to the earthly objects of the scientific age. The concept has expanded to include not only in the Solar System. The ambiguities inherent in defining planets have led to much scientific controversy, the five classical planets, being visible to the naked eye, have been known since ancient times and have had a significant impact on mythology, religious cosmology, and ancient astronomy. In ancient times, astronomers noted how certain lights moved across the sky, as opposed to the fixed stars, ancient Greeks called these lights πλάνητες ἀστέρες or simply πλανῆται, from which todays word planet was derived. In ancient Greece, China, Babylon, and indeed all pre-modern civilizations, it was almost universally believed that Earth was the center of the Universe and that all the planets circled Earth. The first civilization known to have a theory of the planets were the Babylonians
11.
History
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History is the study of the past as it is described in written documents. Events occurring before written record are considered prehistory and it is an umbrella term that relates to past events as well as the memory, discovery, collection, organization, presentation, and interpretation of information about these events. Scholars who write about history are called historians and their works continue to be read today, and the gap between the culture-focused Herodotus and the military-focused Thucydides remains a point of contention or approach in modern historical writing. In Asia, a chronicle, the Spring and Autumn Annals was known to be compiled from as early as 722 BC although only 2nd-century BC texts survived. Ancient influences have helped spawn variant interpretations of the nature of history which have evolved over the centuries, the modern study of history is wide-ranging, and includes the study of specific regions and the study of certain topical or thematical elements of historical investigation. Often history is taught as part of primary and secondary education, the word history comes ultimately from Ancient Greek ἱστορία, meaning inquiry, knowledge from inquiry, or judge. It was in that sense that Aristotle used the word in his Περὶ Τὰ Ζῷα Ἱστορίαι, the ancestor word ἵστωρ is attested early on in Homeric Hymns, Heraclitus, the Athenian ephebes oath, and in Boiotic inscriptions. History was borrowed from Latin into Old English as stær, and it was from Anglo-Norman that history was borrowed into Middle English, and this time the loan stuck. In Middle English, the meaning of history was story in general, the restriction to the meaning the branch of knowledge that deals with past events, the formal record or study of past events, esp. human affairs arose in the mid-fifteenth century. With the Renaissance, older senses of the word were revived, and it was in the Greek sense that Francis Bacon used the term in the sixteenth century. For him, historia was the knowledge of objects determined by space and time, in an expression of the linguistic synthetic vs. analytic/isolating dichotomy, English like Chinese now designates separate words for human history and storytelling in general. In modern German, French, and most Germanic and Romance languages, which are synthetic and highly inflected. The adjective historical is attested from 1661, and historic from 1669, Historian in the sense of a researcher of history is attested from 1531. Historians write in the context of their own time, and with due regard to the current dominant ideas of how to interpret the past, in the words of Benedetto Croce, All history is contemporary history. History is facilitated by the formation of a discourse of past through the production of narrative. The modern discipline of history is dedicated to the production of this discourse. All events that are remembered and preserved in some authentic form constitute the historical record, the task of historical discourse is to identify the sources which can most usefully contribute to the production of accurate accounts of past. Therefore, the constitution of the archive is a result of circumscribing a more general archive by invalidating the usage of certain texts and documents
12.
Astronomical object
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An astronomical object or celestial object is a naturally occurring physical entity, association, or structure that current astronomy has demonstrated to exist in the observable universe. In astronomy, the object and body are often used interchangeably. Examples for astronomical objects include planetary systems, star clusters, nebulae and galaxies, while asteroids, moons, planets, and stars are astronomical bodies. A comet may be identified as both body and object, It is a body when referring to the nucleus of ice and dust. The universe can be viewed as having a hierarchical structure, at the largest scales, the fundamental component of assembly is the galaxy. Galaxies are organized groups and clusters, often within larger superclusters. Disc galaxies encompass lenticular and spiral galaxies with features, such as spiral arms, at the core, most galaxies have a supermassive black hole, which may result in an active galactic nucleus. Galaxies can also have satellites in the form of dwarf galaxies, the constituents of a galaxy are formed out of gaseous matter that assembles through gravitational self-attraction in a hierarchical manner. At this level, the fundamental components are the stars. The great variety of forms are determined almost entirely by the mass, composition. Stars may be found in systems that orbit about each other in a hierarchical organization. A planetary system and various objects such as asteroids, comets and debris. The various distinctive types of stars are shown by the Hertzsprung–Russell diagram —a plot of stellar luminosity versus surface temperature. Each star follows a track across this diagram. If this track takes the star through a region containing a variable type. An example of this is the instability strip, a region of the H-R diagram that includes Delta Scuti, RR Lyrae, the table below lists the general categories of bodies and objects by their location or structure. International Astronomical Naming Commission List of light sources List of Solar System objects Lists of astronomical objects SkyChart, Sky & Telescope Monthly skymaps for every location on Earth
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