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ephemeris

American  
[ih-fem-er-is] / ɪˈfɛm ər ɪs /

noun

plural

ephemerides

  1. a table showing the positions of a heavenly body on a number of dates in a regular sequence.

  2. an astronomical almanac containing such tables.

  3. Archaic. an almanac or calendar.

ephemeris British  
/ ɪˈfɛmərɪs /

noun

  1. a table giving the future positions of a planet, comet, or satellite

  2. an annual publication giving the positions of the sun, moon, and planets during the course of a year, information concerning eclipses, astronomical constants, etc

  3. obsolete a diary or almanac

"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
ephemeris Scientific  
/ ĭ-fĕm′ər-ĭs /

plural

ephemerides

  1. A table giving the coordinates of a celestial body at specific times during a given period. Ephemerides can be used by navigators to determine their longitude while at sea and by astronomers in following objects such as comets. The use of computers has allowed modern ephemerides to determine celestial positions with far greater accuracy than in earlier publications.

Etymology

Origin of ephemeris

1545–55; < Latin ephēmeris day book, diary < Greek ephēmerís diary, account book, derivative of ephḗmeros; ephemeral

Example Sentences

Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.

This is the offset to apply to Chariklo’s ephemeris to fit the observations.

From Nature • Apr. 4, 2014

The astronomical ephemeris is the last outcome of their productive genius.”

From Astronomical Curiosities Facts and Fallacies by Gore, J. Ellard

He checked the time with the satellite ephemeris.

From Pushbutton War by Schoenherr, John

The astronomical part of our ephemeris, therefore, gives the positions of the principal fixed stars, the sun, moon, and all the larger planets at the moment of transit over our own meridian.

From Side-Lights on Astronomy and Kindred Fields of Popular Science by Newcomb, Simon

In some, however, the original plural is not so formed; but is made by changing is to ~ides; as, aphis, aphides; apsis, apsides; ascaris, ascarides; bolis, bolides; cantharis, cantharides; chrysalis, chrysalides; ephemeris, ephemerides; epidermis, epidermides.

From The Grammar of English Grammars by Brown, Goold

Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023

Idioms from The American Heritage® Idioms Dictionary copyright © 2002, 2001, 1995 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company.