Definition of equation of time in US English:

equation of time


  • The difference between mean solar time (as shown by clocks) and apparent solar time (indicated by sundials), which varies with the time of year.

    • ‘You have to combine these two effects to get the true picture, producing a wobbly graph called the equation of time.’
    • ‘Fourier series numerical algorithms were used to compute solar declination and the equation of time.’
    • ‘The equation of time is the difference, over the course of a year, between time as read from a sundial and a clock.’
    • ‘Put all this together, and you have what astronomers call the equation of time, which produces a similar effect around the winter solstice.’