Clock vs. Sun Time

Our clock time differs from sun time. Sun time is the time read by a sundial and measures the time read by the sundial determined from the position of the sun. A solar day is sometimes more or less than 24 hours.

Clock time, on the other hand, is based on there being exactly 24 equal hours in one day. Although this assumption is not correct, it is more convenient in our society to have a time standardization. For example, a person flying from New York to Seattle will know what time it is going to be in Seattle.

The difference between clock and sun time can be calculated using the Equation of Time.