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umbrella

(Encyclopedia)umbrella, a small canopy used as a protection against the sun in China, Egypt, and elsewhere in remote antiquity. It was often an emblem of rank. During the Middle Ages the umbrella became almost exti...

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...

ecliptic

(Encyclopedia)ecliptic ēklĭpˈtĭk, ĭ– [key], the great circle on the celestial sphere that lies in the plane of the earth's orbit (called the plane of the ecliptic). Because of the earth's yearly revolution a...

Cousteau, Jacques Yves

(Encyclopedia)Cousteau, Jacques Yves zhäk ēv ko͞ostōˈ [key], 1910–97, French oceanographer and naval officer. In 1943, with Émil Gagnan, he invented the self-contained underwater breathing apparatus (scuba)...

Baalbek

(Encyclopedia)Baalbek bälˈbĕk [key], ancient city, now in Lebanon, 35 mi (56 km) NW of Damascus, in the Al Biqa (Bekaa) valley. Originally it was probably devoted to the worship of Baal or Bel, the Phoenician su...

Shklovsky, Iosif Samuilovich

(Encyclopedia)Shklovsky, Iosif Samuilovich yôsˈĭf səmo͞oēlˈəvĭch shklŏfˈskē [key], 1916–85, Soviet astronomer. He was head of the department of radio-astronomy at the Sternberg Astronomical Institute,...

Orbiting Solar Observatory

(Encyclopedia)Orbiting Solar Observatory (OSO), series of eight orbiting observatories (see observatory, orbiting) launched between 1962 and 1971 by the National Aeronautics and Space Administration (NASA) to study...

tide

(Encyclopedia)tide, alternate and regular rise and fall of sea level in oceans and other large bodies of water. These changes are caused by the gravitational attraction of the moon and, to a lesser extent, of the s...

sundial

(Encyclopedia)sundial, instrument that indicates the time of day by the shadow, cast on a surface marked to show hours or fractions of hours, of an object on which the sun's rays fall. Although any object whose sha...

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