An Etymological Dictionary of Astronomy and Astrophysics
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A → coordinate time having its spatial origin at the solar system barycenter. It is intended to be used as the independent variable of time for all calculations pertaining to orbits of planets, asteroids, comets, and interplanetary spacecraft in the solar system. → Barycentric Dynamical Time (IDB).

→ barycenter; → coordinate; → time.

A time scale previously used in calculations of the orbits of solar system objects (planets, asteroids, comets, and interplanetary spacecrafts). It was based on the Terrestrial Dynamical Time, but took the relativistic effect of time dilation into account to move the origin to the solar system barycenter. It is now superseded by → Barycentric Coordinate Time (TCB).

→ barycenter; → dynamical; → time.

The → Julian Date referenced to the → barycenter of the → solar system. The BJD is more precise than the → Heliocentric Julian Day because the Sun is not stationary. It moves due to the → gravitational attraction of Jupiter and the other planets.

→ barycentric; → Julian Date.