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sun, in astronomy

(Encyclopedia)CE5 Structure of the sun sun, intensely hot, self-luminous body of gases at the center of the solar system. Its gravitational attraction maintains the planets, comets, and other bodies of the sola...

conjunction, in astronomy

(Encyclopedia)conjunction, in astronomy, alignment of two celestial bodies as seen from the earth. Conjunction of the moon and the planets is often determined by reference to the sun. When a body is in conjunction ...

Vulcan, in astronomy

(Encyclopedia)Vulcan, in astronomy, hypothetical planet whose existence was proposed by Le Verrier to explain part of the advance of the perihelion of Mercury, not all of which could be accounted for by gravitation...

phase, in astronomy

(Encyclopedia)CE5 Phases of the moon phase, in astronomy, the measure of how much of the illuminated surface of a planet or satellite can be seen from a point at a distance from that body; the term is most ofte...

Juno, in astronomy

(Encyclopedia)Juno jo͞oˈnō [key], in astronomy, 3d asteroid to be discovered. It was found in 1804 by C. Harding. It has a diameter of c.120 mi (190 km). Its average distance from the sun is 2.67 astronomical un...

Eris, in astronomy

(Encyclopedia)Eris, in astronomy, the largest known dwarf planet. Eris, whose highly eccentric elliptical orbit ranges from 38 AU to 97 AU and is inclined more than 44°, is the largest known object of the Kuiper b...

Mercury, in astronomy

(Encyclopedia)Mercury, in astronomy, nearest planet to the sun, at a mean distance of 36 million mi (58 million km); its period of revolution is 88 days. Mercury passes through phases similar to those of the moon a...

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 ...

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...

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...