An Etymological Dictionary of Astronomy and Astrophysics

The difference, due to Earth’s elliptical orbit and variable orbital velocity, between apparent solar time and mean solar time. It varies throughout the year, and slightly from year to year. At present, it reaches extremes of about -14 minutes in February, and about +16 minutes in November. The equation of time is visually illustrated by an → analemma.

See also: → equation; → time.