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 It was used from 1960 to 1983 as an astronomical timescale but has been replaced by terrestrial dynamical time and barycentric dynamic time

ephem′eris time`


n.
time measured by the orbital movements of the earth, the moon, and the planets.
[1945–50]
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
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
References in periodicals archive ?
Faced with this problem, astronomers in 1960 instituted Ephemeris Time (ET).
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.