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gravitation
(Encyclopedia)gravitation, the attractive force existing between any two particles of matter. The term gravitygravity is commonly used synonymously with gravitation, but in correct usage a definite distinction is...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...astronomy
(Encyclopedia)astronomy, branch of science that studies the motions and natures of celestial bodies, such as planets, stars, and galaxies; more generally, the study of matter and energy in the universe at large. ...stellar evolution
(Encyclopedia)CE5 The above Hertzsprung-Russell (H-R) diagram shows the track of stellar evolution for a typical star. After spending much of its life evolving toward or along the main sequence, the star becomes...planet
(Encyclopedia)planet [Gr.,=wanderer], a large nonluminous body of rock, gas, or ice that orbits the sun or another star, has a rounded shape due to gravity, and has cleared its orbit of smaller objects. The term, o...Browse by Subject
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