Time is a measurement to determine the duration of an event, or to determine when an event occurred. Time has different incremental scales (year, day, second, etc.), and it has different ways by which it is reported (Greenwich Mean Time, Universal Time, Ephemeris Time, etc.).

Our time scale is based upon the movement of the Sun. Since the Sun appears to move from east to west in the sky, when it is twelve noon in New Jersey, people in Seattle, Washington, say that the Sun has not yet reached its apex, or noontime position. In fact, if you say that the Sun has attained its noontime position, someone who is west of you by one degree of longitude will not see the Sun in its noontime position for approximately four minutes.

In October of 1884, an international agreement divided the planet into 24 time zones (longitudinally into 15° segments), allowing...