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Pandora, in astronomy

(Encyclopedia)Pandora păndôrˈə [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn XVII (or S17), Pandora is an irregularly shaped (nonspherical) body measuring a...

Pallas, in astronomy

(Encyclopedia)Pallas pălˈəs [key], in astronomy, 2d asteroid to be discovered. It was found in 1802 by H. Olbers. The second largest asteroid, it has a diameter of c.300 mi (480 km). Its orbit has a semimajor ax...

Perseus, in astronomy

(Encyclopedia)Perseus, in astronomy, northern constellation lying E of Cassiopeia and N of Taurus. It contains the bright star Mirfak (Alpha Persei) and Algol (Beta Persei), a visible variable star of the type know...

Neptune, in astronomy

(Encyclopedia)Neptune, in astronomy, 8th planet from the sun at a mean distance of about 2.8 billion mi (4.5 billion km) with an orbit lying between those of Uranus and the dwarf planet Pluto; its period of revolut...

Orion, in astronomy

(Encyclopedia)Orion, in astronomy, constellation located on the celestial equator. It is one of the most conspicuous and easily recognizable constellations in the entire sky. From ancient times it has been mentione...

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...

Cassiopeia, in astronomy

(Encyclopedia)Cassiopeia, in astronomy, prominent northern constellation located almost directly opposite the Big Dipper across the north celestial pole. Five bright stars in the constellation form a rough W (or M)...

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...

Tethys , in astronomy

(Encyclopedia)Tethys tēˈthĭs [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn III (or S3), Tethys is 659 mi (1060 km) in diameter, orbits Saturn at a mean dista...

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...