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escape velocity

(Encyclopedia)escape velocity, the velocity a body must be given in order to escape the gravitational hold of some other larger body, e.g., the earth, moon, or sun. A body given less than the escape velocity will f...

Brown, Margaret Wise

(Encyclopedia)Brown, Margaret Wise, 1910–52, American children's book author, b. Brooklyn, N.Y., B.A Hollins College, 1932. Continuing her education at the Bureau of Educational Experiments (now the Bank Street C...

Pickering, William Henry

(Encyclopedia)Pickering, William Henry, 1858–1938, American astronomer, b. Boston, grad. Massachusetts Institute of Technology (B.S., 1879). He taught at the Massachusetts Institute of Technology (1880–87) and ...

cycle

(Encyclopedia)cycle, in astronomy, period of time required for the recurrence of some celestial event. The length of a cycle may be measured relative to the sun or to the fixed stars (see sidereal time). A frequent...

Phobos

(Encyclopedia)Phobos fōˈbŏs [key], in astronomy, innermost moon, or natural satellite, of Mars. ...

Helene

(Encyclopedia)Helene həlēnˈ, hĕlˈənə [key], in astronomy, one of the named moons, or natural satellites, of Saturn. Also known as Saturn XII (or S12), Helene is an irregularly shaped (nonspherical) body meas...

precession of the equinoxes

(Encyclopedia)CE5 Precession of the equinoxes (the points at which the earth's celestial equator intersects its ecliptic) is due to the slow rotation of the earth's axis around a perpendicular to the ecliptic. ...

Cleomedes

(Encyclopedia)Cleomedes klēˌōmēˈdēz, klēˌə– [key], fl. 2d cent., Greek astronomer. In a treatise on the circular theory of heavenly bodies, he recorded several hypotheses, e.g., the earth's spherical for...

Armstrong, Neil Alden

(Encyclopedia)Armstrong, Neil Alden, 1930–2012, American astronaut, b. Wapakoneta, Ohio, grad. Purdue Univ. (B.S., 1955), Univ. of Southern California (M.S., 1970). A U.S. Navy fighter pilot during the Korean War...

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...