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Mitchell, Maria
(Encyclopedia)Mitchell, Maria, 1818–89, American astronomer and educator, b. Nantucket, Mass. Mitchell taught school in Nantucket, and later became a librarian. On Oct. 1, 1847, Mitchell discovered a comet (1847 ...Day, Benjamin Henry
(Encyclopedia)Day, Benjamin Henry, 1810–89, American journalist. He learned the printer's trade in the office of the Springfield (Mass.) Republican and opened a printing office in New York City. Lack of work duri...Tropic of Capricorn
(Encyclopedia)Tropic of Capricorn, parallel of latitude at 23°30′ south of the equator; it is the southern boundary of the tropics. This parallel marks the farthest point south at which the sun can be seen direc...ephemeris time
(Encyclopedia)ephemeris time (ET), astronomical time defined by the orbital motions of the earth, moon, and planets. The earth does not rotate with uniform speed, so the solar day is an imprecise unit of time. Ephe...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...tropics
(Encyclopedia)tropics, also called tropical zone or torrid zone, all the land and water of the earth situated between the Tropic of Cancer at lat. 231⁄2°N and the Tropic of Capricorn at lat. 231⁄2°S. Every po...day
(Encyclopedia)day, period of time for the earth to rotate once on its axis. The ordinary day, or solar day, is measured relative to the sun, being the time between successive passages of the sun over a stationary o...astrology
(Encyclopedia)astrology, form of divination based on the theory that the movements of the celestial bodies—the stars, the planets, the sun, and the moon—influence human affairs and determine the course of event...Pew Charitable Trusts
(Encyclopedia)Pew Charitable Trusts, philanthropic foundation established (1948) by the children of Sun Oil Company founder Joseph N. Pew (1886–1963) of Philadelphia to provide funds for “general religious, cha...Taurus, in astronomy
(Encyclopedia)Taurus [Lat.,= the bull], in astronomy, constellation NW of Orion and lying on the ecliptic (the sun's apparent path through the heavens) between Gemini and Aries; it is one of the constellations of t...Browse by Subject
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