Hours refers to the measure of time equal to the twenty-fourth part of a day, which is the period of time it takes for an astronomical object to rotate on its axis. An example of an astronomical object would be the earth.
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Hours
Hours refers to the measure of time equal to the twenty-fourth part of a day, which is the period of time it takes for an astronomical object to rotate on its axis. An example of an astronomical object would be the earth. |
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There are two kinds of hours: solar (sun) and sideral (star). These correspond to two types of days. The solar hour is presently in use and is divided into sixty minutes. The Egyptians had ten hours of ylight from sunrise to sunset, as shown by a sundial described in 1300 B.C.E., two hours of twilight and twelve hours of night. In time, night became divided into twelve hours. |
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The sidereal hour is used by astronomers and is 9.83 seconds shorter than the solar hour. In astronomy, the hour is a coordinate angle of measure.
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