What is another word for ephemeris time?
Pronunciation: [ɪfˈɛməɹˌɪs tˈa͡ɪm] (IPA) 
Ephemeris time is a time system based on the position of the Earth in its orbit around the Sun. It is also known by other names such as astronomical time, dynamical time and atomic time. Astronomical time is used by astronomers to calculate the positions of celestial objects. Dynamical time is used in the study of the movement of celestial bodies. Atomic time is based on the frequency of radiation from atoms and is the basis for international time standards. Other synonyms for ephemeris time are geocentric time, solar time, and Julian date. These different terms all refer to the same basic principle of measuring time based on the movements of celestial bodies.
