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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...Drummond light
(Encyclopedia)Drummond light: see calcium oxide. ...zodiacal light
(Encyclopedia)zodiacal light or zodiacal band, a faint band of light sometimes seen in the western sky just after sunset in the spring, extending up from the horizon at the point where the sun has just set, or in t...black light
(Encyclopedia)black light: see ultraviolet radiation. ...Rømer, Olaus
(Encyclopedia)Rømer, Olaus or Ole ōläˈo͝os, ōˈlə römˈər [key], 1644–1710, Danish astronomer. He is noted for his discovery that light travels at a definite speed and does not move through space instant...stroboscope
(Encyclopedia)stroboscope strŏbˈəskōp [key], optical instrument for making a moving object appear to be slowed down or stationary. This effect is created by interrupting the observer's view so that the object i...Tamm, Igor Yevgenyevich
(Encyclopedia)Tamm, Igor Yevgenyevich, 1895–1971, Soviet physicist, Ph.D. Moscow State Univ., 1933. He was a researcher at the P. N. Lebedev Physical Institute in Moscow from 1934 until his death in 1971. Tamm an...Frank, Ilya Mikhailovich
(Encyclopedia)Frank, Ilya Mikhailovich, 1908–90, Soviet physicist, Ph.D. Moscow State Univ., 1935. He was a professor at Moscow State Univ. from 1944 until his death in 1990. Mikhailovich and Igor Y. Tamm won the...Arabian horse
(Encyclopedia)Arabian horse, breed of light horse developed in Mesopotamia and N Africa, and probably the first true domesticated breed. Prized since earliest times for its superior beauty, spirit, speed, grace of ...motion
(Encyclopedia)motion, the change of position of one body with respect to another. The rate of change is the speed of the body. If the direction of motion is also given, then the velocity of the body is determined; ...Browse by Subject
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