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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...

chemosynthesis

(Encyclopedia)chemosynthesis, process in which carbohydrates are manufactured from carbon dioxide and water using chemical nutrients as the energy source, rather than the sunlight used for energy in photosynthesis....

wave, in physics

(Encyclopedia)wave, in physics, the transfer of energy by the regular vibration, or oscillatory motion, either of some material medium or by the variation in magnitude of the field vectors of an electromagnetic fie...

light-year

(Encyclopedia)light-year, in astronomy, unit of length equal to the distance light travels in one sidereal year. It is 9.461 × 1012 km (about 6 million million mi). Alpha Centauri and Proxima Centauri, the stars n...

doldrums

(Encyclopedia)doldrums dŏlˈdrəmz [key] or equatorial belt of calms, area around the earth centered slightly north of the equator between the two belts of trade winds. The large amount of solar radiation that arr...

Oort, Jan Hendrik

(Encyclopedia)Oort, Jan Hendrik ōrt [key], 1900–1992, Dutch astronomer. He confirmed (1927) Bertil Lindblad's theory of the Milky Way galaxy's rotation. In the 1950s he and his colleagues used radio astronomical...

Mount Wilson Observatory

(Encyclopedia)Mount Wilson Observatory, astronomical observatory located in California on Mt. Wilson, near Pasadena. Mt. Wilson Observatory was founded in 1904 by George E. Hale. Its equipment includes 100-in. (2.5...

Bode's law

(Encyclopedia)Bode's law [for J. E. Bode], also known as Titius's law or the Titius-Bode law, empirical relationship between the mean distances of the planets from the sun. If each number in the series 0, 3, 6, 12,...

stellar structure

(Encyclopedia)stellar structure, physical properties of a star and the processes taking place within it. Except for that of the sun, astronomers must draw their conclusions regarding stellar structure on the basis ...

diode

(Encyclopedia)diode dīˈōd [key], two-terminal electronic device that permits current flow predominantly in only one direction. Most diodes are semiconductor devices; diode electron tubes are now used only for a ...