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occultation

(Encyclopedia)occultation ŏkˌəltāˈshən [key], in astronomy, eclipse of one celestial body by another, e.g., when the moon lies between a star and the earth. Occultations of stars by the moon are important in ...

Port Augusta

(Encyclopedia)Port Augusta, city (2016 pop. 13,808), South Australia, S Australia, at the head of Spencer Gulf. It is a railroad center and a center for solar and other renewable energy. ...

anomalistic year

(Encyclopedia)anomalistic year ənŏmˌəlĭsˈtĭk [key], time required for the earth to go from the perihelion point once around the sun and back to the perihelion point. It is 365 days, 6 hr, 13 min, 53.0 sec of...

Foch, Ferdinand

(Encyclopedia)Foch, Ferdinand fĕrdēnäNˈ fôsh [key], 1851–1929, marshal of France. A professor at the École de Guerre, he later served (1908–11) as director of that institute. In World War I, he was respon...

Al-Battani

(Encyclopedia)Al-Battani ălˌbətēˈnēəs [key], b. before 858, d. 929, Arab astronomer and mathematician. He is best known in astronomy for his improvements and corrections of the Ptolemaic tradition. His Kitab...

Haleakala Observatories

(Encyclopedia)Haleakala Observatories häˌlāäˌkäläˈ [key], astronomical facilities located on the summit of Haleakala volcano, 10,023 ft (3,055 m), in Haleakala National Park, Maui island, Hawaii. Because of...

Chamberlin, Thomas Chrowder

(Encyclopedia)Chamberlin, Thomas Chrowder, 1843–1928, American geologist, b. Mattoon, Ill., grad. Beloit College, 1866. He was professor of geology at Beloit (1873–82), president of the Univ. of Wisconsin (1887...

sidereal time

(Encyclopedia)sidereal time (ST), time measured relative to the fixed stars; thus, the sidereal day is the period during which the earth completes one rotation on its axis so that some chosen star appears twice on ...

observatory, orbiting

(Encyclopedia)observatory, orbiting, research satellite designed to study solar radiation, electromagnetic radiation from distant stars, the earth's atmosphere, or the like. Because the atmosphere and other aspects...

planetesimal theory

(Encyclopedia)planetesimal theory plănˌĭtĕsˈəməl [key]: see solar system. ...