| ephemeris time n. A highly accurate astronomical system for the measurement of time based on the period of Earth's orbit, but in practice relying on lunar observations and an accurate lunar ephemeris. |
ephemeris time
n
(Miscellaneous Technologies / 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 1/31 556 925.9747 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 It was used from 1960 to 1983 as an astronomical timescale but has been replaced by terrestrial dynamical time and barycentric dynamic time See TDT, TDB
| ephemeris time A highly accurate astronomical system for the measurement of time based in theory on the period of Earth's orbit, but in practice relying on lunar observations and an accurate lunar ephemeris so as to not be subject to the irregularities of Earth's rotation. The year 1900 CE is considered a standard year, containing 31,556,925.9747 seconds of ephemeris time. |
ThesaurusLegend: Synonyms Related Words Antonyms
| 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 motionsastronomy, 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 |
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