Ephemerides
Ephemerides are tables or datasets listing the calculated positions of the Sun, Moon and planets for given points in time. They are the astronomical basis of every horoscope.
The word comes from the Greek ephēmeros ("for a day"): ephemerides list, day by day, where the celestial bodies stand as seen from Earth — usually as ecliptic longitude in degrees, that is, as a position in the zodiac. Historically they were published as printed tables; today they come from numerical models of celestial mechanics, the same planetary theories that spacecraft navigation relies on.
In astrology, ephemerides are the foundation of every calculation: without them, neither a natal chart nor a transit can be determined. A properly calculated chart takes a date, time and place, looks up the planetary positions in the ephemerides (or computes them directly) and plots them on the zodiac.
Ephemerides supply calculated astronomical positions. Astrological meaning comes only from a separate system of interpretation; it is not part of the ephemerides themselves.
How we use this term
Leitstern calculates planetary positions with Astronomy Engine and shows angles and orbs separately from the astrological reading.
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