ephemeris time(redirected from Ephemeris second)
Also found in: Thesaurus, Encyclopedia.
(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 It was used from 1960 to 1983 as an astronomical timescale but has been replaced by terrestrial dynamical time and barycentric dynamic time
time measured by the orbital movements of the earth, the moon, and the planets.
Switch to new thesaurus
|Noun||1.||ephemeris 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