ephemeris time


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ephemeris time

n
(Horology) time that is based on the orbit of the earth around the sun rather than the axial rotation of the earth, one ephemeris second being 556 925.9747 of the tropical year 1900. It was used from 1960 to 1983 as an astronomical timescale but has been replaced by terrestrial dynamical time and barycentric dynamic time
Collins English Dictionary – Complete and Unabridged, 12th Edition 2014 © HarperCollins Publishers 1991, 1994, 1998, 2000, 2003, 2006, 2007, 2009, 2011, 2014

ephem′eris time`


n.
time measured by the orbital movements of the earth, the moon, and the planets.
[1945–50]
Random House Kernerman Webster's College Dictionary, © 2010 K Dictionaries Ltd. Copyright 2005, 1997, 1991 by Random House, Inc. All rights reserved.
ThesaurusAntonymsRelated WordsSynonymsLegend:
Noun1.ephemeris time - (astronomy) a measure of time defined by Earth's orbital motionephemeris time - (astronomy) a measure of time defined by Earth's orbital motion; terrestrial time is mean solar time corrected for the irregularities of the Earth's motions
TDT, terrestrial dynamical time, terrestrial time, TT
astronomy, uranology - the branch of physics that studies celestial bodies and the universe as a whole
time unit, unit of time - a unit for measuring time periods
Based on WordNet 3.0, Farlex clipart collection. © 2003-2012 Princeton University, Farlex Inc.
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References in periodicals archive ?
Ephemeris time was determined by measuring the position of the Moon with respect to several surrounding stars.
A Historical Review of U.S. Contributions to the Atomic Redefinition of the SI Second in 1967
His distinguished career included contributions to such fields as radio navigation (LORAN), the definition of Ephemeris Time, and the orbit of Mars (S&T: April 1975, page 215).
"Ill met by moonlight"
For greatest precision, especially in the distant past or future, you can specify your own value of |Delta~T -- the difference between Universal Time and Ephemeris Time caused by the slowing of the Earth's rotation.
TotalEclipse

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