bn:00025347n
Noun Concept
Categories: Articles with permanently dead external links, Articles with short description, Astronomical epochs
EN
epoch  date of reference
EN
(astronomy) an arbitrarily fixed date that is the point in time relative to which information (as coordinates of a celestial body) is recorded WordNet 3.0
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EN
(astronomy) an arbitrarily fixed date that is the point in time relative to which information (as coordinates of a celestial body) is recorded WordNet 3.0 & WordNet 2020
In astronomy, an epoch is a moment in time used as a reference point for some time-varying astronomical quantity, such as the celestial coordinates or elliptical orbital elements of a celestial body, because these are subject to perturbations and vary with time. Wikipedia
A moment in time used as a reference for the orbital elements of a celestial body Wikipedia Disambiguation
Moment in time used as a reference point for some time-varying astronomical quantity Wikidata
Moment in history which is usually marked by some significant event. OmegaWiki
A precise instant of time that is used as a point of reference. Wiktionary
( astronomy) time reference point. Wiktionary (translation)