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Algol, in astronomy

(Encyclopedia)Algol ălˈgŏl [key], famous variable star in the constellation Perseus; Bayer designation β Persei; 1992 position R.A. 3h07.7m, Dec. +40°55′. Algol's variation in apparent magnitude, from 2.06 t...

Dione, in astronomy

(Encyclopedia)Dione dīōˈnē [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn IV (or S4), Dione is 695 mi (1,120 km) in diameter, orbits Saturn at a mean distanc...

Hercules, in astronomy

(Encyclopedia)Hercules hûrˈkyəlēzˌ [key], in astronomy, northern constellation located between Lyra and Corona Borealis. It is traditionally depicted as the hero Hercules in a kneeling position. There are no v...

Calypso, in astronomy

(Encyclopedia)Calypso, in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn XIV (or S14), Calypso is a small, irregularly shaped (nonspherical) body measuring about 21 mi (34...

Cancer, in astronomy

(Encyclopedia)Cancer [Lat.,=the crab], in astronomy, constellation lying on the ecliptic (the sun's apparent path through the heavens) between Gemini and Leo; it is a constellation of the zodiac. It contains the st...

Ceres, in astronomy

(Encyclopedia)Ceres sîrˈēz [key], in astronomy, a dwarf planet, the first asteroid to be discovered. It was found on Jan. 1, 1801, by G. Piazzi. He took three distinct observations; on the basis of these the mat...

Venus, in astronomy

(Encyclopedia)Venus, in astronomy, 2d planet from the sun; it is often called the evening star or morning star and is brighter than any object in the sky except the sun and the moon. Because its orbit lies between ...

Vesta, in astronomy

(Encyclopedia)Vesta vĕsˈtə [key], in astronomy, the fourth asteroid to be discovered. It was found in 1807 by H. Olbers. It is the third largest asteroid in size, with a diameter of c.326 mi (525 km). Its averag...

Castor, in astronomy

(Encyclopedia)Castor kăsˈtər [key], bright star in the constellation Gemini; Bayer designation α Geminorum; 1992 position R.A. 7h34.1m, Dec. +31°54′. Slightly dimmer than Pollux, with which it forms the Twin...

X-ray astronomy

(Encyclopedia)X-ray astronomy, study of celestial objects by means of the X rays they emit, in the wavelength range from 0.01 to 10 nanometers. X-ray astronomy dates to 1949 with the discovery that the sun emits X ...
 

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