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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...

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...

Mimosa, in astronomy

(Encyclopedia)Mimosa or Beta Crucis bāˈtə kro͞oˈsĭs [key], bright star in the constellation Crux (Southern Cross); 1992 position R.A. 12h47.3m, Dec. −59°39′. It is sometimes called Becrux, from its Bayer...

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...

Leo, in astronomy

(Encyclopedia)Leo [Lat.,=the lion], northern constellation lying S of Ursa Major and on the ecliptic (apparent path of the sun through the heavens) between Cancer and Virgo; it is one of the constellations of the z...

Larissa, in astronomy

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

Ariel, in astronomy

(Encyclopedia)Ariel ârˈēəl [key], in astronomy, one of the moons, or natural satellites, of Uranus. ...

Leda, in astronomy

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

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...