equation of timeequation of time
Astron. the constantly changing difference between the true sundial (apparent solar time) and mean solar time: the apparent solar time may be as much as 16 minutes ahead or behind
equation of time
The difference between time measured from the observed position of the sun and time measured from the position of the mean sun, caused by changes in the earth's orbital speed through the cycle of the seasons. It is the difference between time measured with a sundial and time measured with a clock.