"Equation of Time", one of the most interesting complications in the history of traditional watchmaking, is the guest of today, where we give technical terms and expressions about watches.
In our everyday life, there are two different measurements for time that we have determined with reference to the sun; apparent solar time and mean solar time.
The apparent solar time periodically advances and continues at constant speed. Just like the hands in our watch that constantly move at the same speed ... On the other hand, the mean solar time is variable and a difference of -20 to +30 seconds may occur between the apparent solar time and mean solar time on any day of the year.
These differences, which are added on a daily basis, can be caused by deviations exceeding 15 minutes at various times of the year. These differences are 16 minutes 33 seconds in favor of mean solar time on November 3 and 14 minutes 6 seconds around 12 February in favor of the apparent solar time . On 15 April, 1 September, 13 June, 25 December, the difference is almost 0. If the calculation is made on a yearly basis, the difference between the apparent solar time and mean solar time is zero, i.e. the average of the deviations within the year resets itself in 365 days.
The reason for this difference stems from the inclination of the earth on the equatorial and elliptical axis. At this point, we have watches with "Equation of Time" complication which shows us the difference between apparent solar time and mean solar time.