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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...Astronomical Ephemeris
(Encyclopedia)Astronomical Ephemeris: see ephemeris. ...American Ephemeris and Nautical Almanac
(Encyclopedia)American Ephemeris and Nautical Almanac: see ephemeris. ...ephemeris
(Encyclopedia)ephemeris ĭfĕmˈərĭs [key] (pl., ephemerides), table listing the position of one or more celestial bodies for each day of the year. The French publication Connaissance de Temps is the oldest of th...second
(Encyclopedia)second, abbr. sec or s, fundamental unit of time in all systems of measurement. In practical terms, the second is 1/60 of a minute, 1/3,600 of an hour, or 1/86,400 of a day. Since the length of the da...Nautical Almanac
(Encyclopedia)Nautical Almanac: see ephemeris. ...Davis, Charles Henry
(Encyclopedia)Davis, Charles Henry, 1807–77, American naval officer and scientist, b. Boston. Appointed a midshipman in 1823, Davis directed operations of the Coast Survey for a time along the New England coast. ...United States Naval Observatory
(Encyclopedia)United States Naval Observatory, a federal astronomical observatory, located in Washington, D. C. It evolved from the Navy's oldest scientific institution, the Depot of Charts and Instruments, founded...almanac
(Encyclopedia)almanac, originally, a calendar with notations of astronomical and other data. Almanacs have been known in simple form almost since the invention of writing, for they served to record religious feasts...time , sequential arrangement of all events
(Encyclopedia)time, sequential arrangement of all events, or the interval between two events in such a sequence. The concept of time may be discussed on several different levels: physical, psychological, philosophi...Browse by Subject
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