Ephemeris

Calculations have evolved from using Earth’s variable rotation (Universal Time) to highly uniform scales like Ephemeris Time (ET) and its successors, Terrestrial Time (TT) and Barycentric Dynamical Time (TDB), which incorporate relativistic corrections. Leading Sources and Software

Times of solar/lunar eclipses, planetary ingresses (moving into a new sign), and retrograde motion. Ephemeris

While printed almanacs are still produced for emergency use, most professionals use electronic datasets: Ephemeris - an overview | ScienceDirect Topics Derived from the Greek word for "diary," it

An (plural: ephemerides ) is a tabulation of the computed positions and velocities of celestial bodies—such as planets, moons, asteroids, and satellites—at specific dates and times. Derived from the Greek word for "diary," it serves as an itinerary for astronomical objects, providing essential data for navigation, scientific research, and astrology. Core Applications Scientific versions often include:

Astrologers use these tables to track planetary "transits" (the movement of planets through zodiac signs) and generate birth charts. Scientific and Technical Data

An ephemeris provides more than just a location in the sky. Scientific versions often include: