Ephemeris

An ephemeris is a table or database containing the calculated positions of celestial objects (such as the Sun, Moon, planets, and stars) over time. It provides highly accurate positional data, usually at regular intervals, allowing astronomers, navigators, and others to predict the location of these objects at specific points in the future or determine their past positions. Ephemerides are crucial for a variety of applications, including astronomical observations, space navigation, timekeeping, and even the calculation of tidal patterns. The level of detail and the specific data provided in an ephemeris can vary depending on its intended use.

Ephemeris meaning with examples

• Astronomers relied on the planetary ephemeris to track the precise positions of Jupiter and its moons during the transit of the Galilean satellites. The ephemeris ensured the telescope was correctly aimed, enabling successful observation. This real-time data facilitated the accurate calculation of the planet's movements and orbital characteristics throughout the duration of the observation.
• A navigator uses an ephemeris to determine the positions of the sun and stars for celestial navigation. By comparing these calculated positions to observed angles, a ship's location at sea can be determined with remarkable precision. These calculations, used for centuries, are foundational for maritime navigation.
• Software used to predict the next solar eclipse relies heavily on extremely precise ephemerides of the Sun, Moon and Earth. This allows a calculation of the point of totality, path and timing with stunning accuracy. Without ephemerides, such predictions would be impractical to impossible.
• Amateur astronomers often consult an ephemeris to locate planets, comets, and asteroids in the night sky. The ephemeris provides essential information like right ascension and declination at the time of observation, making it easier to find these objects even with basic telescopes.