Definition:
An ephemeris is a table or almanac that provides the calculated positions of celestial bodies at specific times. It serves as a crucial reference for astronomers, navigators, and astrologers, offering precise data on the locations of stars, planets, moons, and artificial satellites, facilitating observation, navigation, and the casting of horoscopes.
Etymology & Origin:
The term “ephemeris” comes from the Latin “ephemeris,” which itself is derived from the Greek word “ephēmeros,” meaning “daily.” Historically, ephemerides were daily tables or diaries of celestial observations. The concept dates back to antiquity, with its usage evolving over centuries to refer to detailed annual publications of celestial predictions.
Examples:
- Astronomical ephemerides, which include data such as planetary positions for each day of the year, used by astronomers for planning observations.
- Nautical ephemerides, essential for celestial navigation at sea, providing positions of the sun, moon, planets, and stars.
- The Astronomical Almanac, published annually, provides an ephemeris of the sun, moon, planets, and other celestial phenomena, used globally by astronomers and navigators.
