How are ephemerides used?
Ephemerides are used to predict astronomical events.
Ephemerides contain the information required to predict the position of astronomical bodies such as the Earth, Moon, Sun and other planets. They take the form of tables, equations or data which can predict positions accurately.
The most accurate modern ephemerides are the DE430 data sets from NASA. The data consists of terms for Chebyshev polynomials which can calculate the positions of bodies to a high degree of accuracy.
Ephemerides are typically used to calculate the times of sunrise and sunset, moon rise and moon set, solstices, equinoxes, apses, moon phases and eclipses.