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helium

(Encyclopedia)helium hēˈlēəm [key], gaseous chemical element; symbol He; at. no. 2; at. wt. 4.0026; m.p. below −272℃ at 26 atmospheres pressure; b.p. −268.934℃ at 1 atmosphere pressure; density 0.1785 g...

chromosphere

(Encyclopedia)chromosphere krōˈməsfērˌ [key] [Gr.,=color sphere], layer of rarefied, transparent gases in the solar atmosphere; it measures 6,000 mi (9,700 km) in thickness and lies between the photosphere (th...

Newton, Sir Isaac

(Encyclopedia)Newton, Sir Isaac, 1642–1727, English mathematician and natural philosopher (physicist), who is considered by many the greatest scientist that ever lived. Newton was his university's representa...

nucleosynthesis

(Encyclopedia)nucleosynthesis or nucleogenesis, in astronomy, production of all the chemical elements from the simplest element, hydrogen, by thermonuclear reactions within stars, supernovas, and in the big bang at...

bivalve

(Encyclopedia)CE5 Internal anatomy of a clam, Anodonta, representative mollusk of the class Pelecypoda (the bivalves) bivalve, aquatic mollusk of the class Pelecypoda (“hatchet-foot”) or Bivalvia, with a la...

Jupiter, in astronomy

(Encyclopedia)Jupiter jo͞oˈpətər [key], in astronomy, 5th planet from the sun and largest planet of the solar system. Astronomers have discovered 79 satellites orbiting Jupiter, but five of those, small sate...

meteorite

(Encyclopedia)meteorite, meteor that survives the intense heat of atmospheric friction and reaches the earth's surface. Because of the destructive effects of this friction, only the very largest meteors become mete...

hydrogen bomb

(Encyclopedia)hydrogen bomb or H-bomb, weapon deriving a large portion of its energy from the nuclear fusion of hydrogen isotopes. In an atomic bomb, uranium or plutonium is split into lighter elements that togethe...

sound recording

(Encyclopedia)sound recording, process of converting the acoustic energy of sound into some form in which it can be permanently stored and reproduced at any time. In 1855 the inventor Leon Scott constructed a devic...

marriage

(Encyclopedia)marriage, socially sanctioned union that reproduces the family. In all societies the choice of partners is generally guided by rules of exogamy (the obligation to marry outside a group); some societie...