|—n , pl ephemerides|
|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|
|[C16: from Latin, from Greek: diary, journal; see |
|ephemeris (ĭ-fěm'ər-ĭs) Pronunciation Key
Plural ephemerides (ěf'ə-měr'ə-dēz')
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.