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light-year
light-year in astronomy, unit of length equal to the distance light travels in one sidereal year . It is 9.461 × 10 12 km (about 6 million million mi). Alpha Centauri and Proxima Centauri, the stars nearest our solar system, are about 4.3 light-years distant. See also parsec .
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refugee
refugee one who leaves one's native land either because of expulsion or to escape persecution. The legal problem of accepting refugees is discussed under asylum ; this article considers only mass dislocations and the organizations that help refugees.
The Rise of International Refugee Organiz...
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Quechua
Quechua Kechua , or Quichua , linguistic family belonging to the Andean branch of the Andean-Equatorial stock of Native American languages (mainly in South America). Encompassing far more native speakers than any other aboriginal language group in the Americas, the languages of the Que...
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Bantu languages
Bantu languages group of African languages forming a subdivision of the Benue-Niger division of the Niger-Congo branch of the Niger-Kordofanian language family (see African languages ). Bantu contains hundreds of languages that are spoken by 120 million Africans in the Congo Basin, Angola, the Rep...
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wilderness
wilderness land retaining its primeval character with the imprint of humans minimal or unnoticeable. In the United States, the Wilderness Act of 1964 established the National Wilderness Preservation System with a nucleus of 9 million acres (3.6 million hectares) of land in 54 different areas, mostl...
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Native American languages
Native American languages languages of the native peoples of the Western Hemisphere and their descendants. A number of the Native American languages that were spoken at the time of the European arrival in the New World in the late 15th cent. have become extinct, but many of them are still in use to...
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human evolution
human evolution theory of the origins of the human species, Homo sapiens. Modern understanding of human origins is derived largely from the findings of paleontology , anthropology , and genetics , and involves the process of natural selection (see Darwinism ). Although gaps in the fossil reco...
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Gadsden Purchase
Gadsden Purchase gădz´den , strip of land purchased (1853) by the United States from Mexico. The Treaty of Guadalupe Hidalgo (1848) had described the U.S.-Mexico boundary vaguely, and President Pierce wanted to insure U.S. possession of the Mesilla Valley near the Rio Grande—the mo...
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Treaty of Guadalupe Hidalgo
Treaty of Guadalupe Hidalgo 1848, peace treaty between the United States and Mexico that ended the Mexican War . Negotiations were carried on for the United States by Nicholas P. Trist . The treaty was signed on Feb. 2, 1848, in the village of Guadalupe Hidalgo, just outside Mexico City. It confi...
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parsec
parsec [ par allax + sec ond], in astronomy, basic unit of length for measuring interstellar and intergalactic distances, equal to 206,265 times the distance from the earth to the sun, 3.26 light-years, or 3.08 × 10 13 km (about 19 million million mi). The distan...
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