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Pluto, in astronomy

(Encyclopedia)Pluto, in astronomy, a dwarf planet and the first Kuiper belt, or transneptunian, object (see comet) to be discovered (1930) by astronomers. Pluto has an elliptical orbit usually lying beyond that of ...

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...

radar astronomy

(Encyclopedia)radar astronomy, application of radar to the determination of distances and planetary features within the solar system, such as rotation rates. A short burst of radio waves is transmitted in the direc...

Jupiter, in astronomy

(Encyclopedia)Jupiter jo͞oˈpətər [key], in astronomy, 5th planet from the sun and largest planet of the solar system. Astronomers have discovered 79 satellites orbiting Jupiter, but five of those, small sate...

Saturn, in astronomy

(Encyclopedia)CE5 Saturn and its ring system as seen from Earth Saturn, in astronomy, 6th planet from the sun. Saturn has 82 confirmed natural satellites, many of which have not been named. Five of the discov...

ether, in physics and astronomy

(Encyclopedia)ether or aether, in physics and astronomy, a hypothetical medium for transmitting light and heat (radiation), filling all unoccupied space; it is also called luminiferous ether. In Newtonian physics a...

Aquila, in astronomy

(Encyclopedia)Aquila [Lat.,=the eagle], equatorial constellation located N of Sagittarius and Capricornus, lying partly in the Milky Way. It is sometimes depicted as an eagle. It contains the bright star Altair (Al...

radio astronomy

(Encyclopedia)radio astronomy, study of celestial bodies by means of the electromagnetic radio frequency waves they emit and absorb naturally. Radio waves also come from outside the Milky Way. These extragalact...

constellation, in astronomy

(Encyclopedia)CE5 Constellations: Southern sky CE5 Constellations: Southern sky CE5 Constellations: Southern sky constellation, in common usage, group of stars that appear to form a configuration in the...

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...