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* [[Wikisource:Ephemeris of Saturn|Ephemeris of Saturn]]
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An '''ephemeris''' (plural: '''ephemerides''') (from the [[Greek language|Greek]] word ''ephemeros''= daily) was, traditionally, a table providing the positions (given in a [[Cartesian coordinate system]], or in [[right ascension]] and [[declination]] or, for astrologers, in [[longitude]] along the [[zodiac]]al [[ecliptic]]), of the [[Sun]], the [[Moon]], and the [[planet]]s in the [[sky]] at a given moment in [[time]]; the astrological positions are usually given for either [[noon]] or [[midnight]] depending on the particular ephemeris that is used. In [[1554]], [[Johannes Stadius]] published a well-known work known as ''Ephemerides novae at auctae'' that attempted to give accurate planetary positions.
For scientific uses, a modern planetary ephemeris comprises software that generates positions of the planets and often of their satellites, or of [[asteroid]]s or [[comet]]s at virtually any time desired by the user. Often there is an option to find the velocities of the bodies of interest, as well. Typically, such ephemerides cover several, or even many centuries, past and future; the future ones can be covered because [[celestial mechanics]] is an accurate theory. The biggest uncertainties, nowadays, are due to the perturbations on the [[planet]]s of numerous [[asteroids]], most of whose masses are poorly known, rendering their effect a bit uncertain.
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An ephemeris also sometimes provides data on [[astronomy|astronomical]] phenomena of interest to [[astrologer]]s and [[astronomers]] such as [[solar]] and [[lunar]] [[eclipse]]s, apparent [[retrogradation]]/[[planetary stations]], [[planetary]] ingresses, [[sidereal time]], positions for the Mean and True [[Lunar node|nodes of the moon]], the [[phases of the Moon]], and sometimes even the position(s) of [[2060 Chiron|Chiron]], [[Lilith]], and other minor [[celestial bodies]]. Some ephemerides also contain a monthly [[astrological aspects|aspectarian]], while others often include the [[declination]] of the planets as well as their longitudes, [[right ascension]]s or [[Cartesian coordinates]].
Though [[astrology]] is and always has been [[geocentric]], [[Heliocentric|heliocentric]] Astrology is an emerging field; for this purpose a standard ephemeris cannot be utilized, and because of this specialized heliocentric ephemerides must be calculated and used instead of the default geocentric ephemerides that are used in standard [[Western astrology]] to construct the [[horoscope|astrological chart]]/[[natal chart]].
==Literature==
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