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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...

Naiad, in astronomy

(Encyclopedia)Naiad, in astronomy, one of the natural satellites, or moons, of Neptune. ...

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...

Pan, in astronomy

(Encyclopedia)Pan, in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn XVIII (or S18), Pan is 12.5 mi (20 km) in diameter, orbits Saturn at a mean distance of 83,000 mi (133...

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...

Pegasus, in astronomy

(Encyclopedia)Pegasus pĕgˈəsəs [key], in astronomy, northern constellation lying SW of Andromeda and SE of Cygnus. It is named for the mythological winged horse Pegasus. The constellation is easily recognized b...

Pasiphaë, in astronomy

(Encyclopedia)Pasiphaë pəsĭfˈəēˌ [key], in astronomy, one of the 39 known moons, or natural satellites, of Jupiter. ...

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...

Mars, in astronomy

(Encyclopedia)Mars, in astronomy, 4th planet from the sun, with an orbit next in order beyond that of the earth. Mars has two natural satellites, discovered by Asaph Hall in 1877. The innermost of these, Phobos...

Leda, in astronomy

(Encyclopedia)Leda lēˈdə [key], in astronomy, one of the 39 known moons, or natural satellites, of Jupiter. ...