Mean Time (Noun)

(astronomy) time based on the motion of the mean sun (an imaginary sun moving uniformly along the celestial equator).

Nouns denoting time and temporal relations.

The clocks at the observatory were set to mean time, allowing astronomers to track celestial events with precision.
Mean time is used as the basis for calculating solar time, which is the time kept by the Earth's rotation relative to the Sun.
In astronomy, mean time is used to specify the time of day or night when a particular celestial event occurs.
The sidereal day, based on the mean time system, is the time it takes the Earth to rotate once on its axis relative to the stars.
To correct for the variations in the Earth's rotation, astronomers use mean time to calculate the position of the planets and other celestial bodies.