Measures the variation of the lengths of days throughout a year. For example, during parts of the year, days can fluctuate by around 20 seconds above or below 24 hours. This is caused by the Earth?s orbit around the sun being slightly elliptical and the sun?s eastward passage throughout the year being fastest at the solstices and slowest at the equinoxes. Clocks and watches, however, measure time at a steady rate, known as mean time, while solar time fluctuates as mentioned above ? the equation of time is the offset between mean time and solar timeEquation of time
