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hour angle

(Encyclopedia)hour angle, in astronomy, a coordinate in the equatorial coordinate system. The hour angle of a celestial body is the angular distance, expressed in hours, minutes, and seconds (one hour equals 15 deg...

Moscow State University

(Encyclopedia)Moscow State University, at Moscow, Russia, officially M. V. Lomonosov Moscow State Univ.; founded 1755 as Moscow Univ. by the Russian scientist M. V. Lomonosov, renamed Moscow State Univ. after the R...

parsec

(Encyclopedia)parsec pärˈsĕc [key] [parallax + second], in astronomy, basic unit of length for measuring interstellar and intergalactic distances, equal to 206,265 times the distance from the earth to the su...

nutation

(Encyclopedia)nutation, in astronomy, a slight wobbling motion of the earth's axis. The causes of nutation are similar to those of the precession of the equinoxes, involving the varying attraction of the moon on th...

Cauchy, Augustin Louis, Baron

(Encyclopedia)Cauchy, Augustin Louis, Baron ōgüstăNˈ lwē bärôNˈ kōshēˈ [key], 1789–1857, French mathematician. He was professor simultaneously (1816–30) at the École polytechnique, the Sorbonne, and...

syzygy

(Encyclopedia)syzygy sĭzˈəjē [key], in astronomy, alignment of three bodies of the solar system along a straight or nearly straight line. A planet is in syzygy with the earth and sun when it is in opposition or...

Abbe, Cleveland

(Encyclopedia)Abbe, Cleveland ăbˈē [key], 1838–1916, American meteorologist, b. New York City; brother of Robert Abbe. He was the first official daily weather forecaster in the United States. Abbe studied astr...

Picard, Jean

(Encyclopedia)Picard, Jean, 1620–82, French astronomer, noted for having made the first accurate measurement of a degree of the earth's meridian. The figures he established were of great value to Newton in his ca...

Hubble Space Telescope

(Encyclopedia)Hubble Space Telescope (HST), the first large optical orbiting observatory. Built from 1978 to 1990 at a cost of $1.5 billion, the HST (named for astronomer E. P. Hubble) was expected to provide the c...

fluorescence

(Encyclopedia)fluorescence flo͝orĕsˈəns [key], luminescence in which light of a visible color is emitted from a substance under stimulation or excitation by light or other forms of electromagnetic radiation or ...