time measured by the orbital movements of the earth, the moon, and the planets.
Super Spooky Night Time WordsWhether you like nightfall or not, these literary words help capture its truest form, ranging from spooky to serene, and everything in between.
Is It “Sometime,” “Sometimes,” Or “Some Time”?While they appear very similar, sometime, sometimes, and some time have slightly different meanings. Sometime means a vague point in time, and usually refers to a long amount of time. Sometimes means occasionally. Some time refers to a period of time. Sometime Sometime refers to an unspecified point in time. It functions as an adverb, and is also synonymous with someday, one day, or sooner …
Origin of ephemeris time
First recorded in 1945–50
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
British Dictionary definitions for ephemeris time
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 It was used from 1960 to 1983 as an astronomical timescale but has been replaced by terrestrial dynamical time and barycentric dynamic time
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Science definitions for 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.