solar time

American  

[soh-ler tahym] / ˈsoʊ lər ˌtaɪm /

noun

1. Astronomy. time determined according to the position of the sun; either apparent time or mean solar time.

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solar time Scientific  

1. Time based on the rotation of the Earth with respect to the Sun. Solar time units are slightly longer than sidereal units due to the continuous movement of the Earth along its orbital path. For example, by the time the Earth has completed one full rotation on its axis with respect to the fixed stars, it has also moved a short distance in its orbit and is oriented slightly differently to the Sun, so that it must turn slightly more on its axis to complete a full rotation with respect to the Sun.

2. ◆ The time it takes the Earth to rotate fully with respect to the Sun is called a solar day. The length of a solar day varies throughout the year due to variations in the Earth's orbital speed and other factors.

3. ◆ The average value of all solar days in the solar year is called a mean solar day; it is 24 hours long and by convention is measured from midnight to midnight.

4. ◆ A solar year is the period of time required for the Earth to make a complete orbit with respect to the Sun as measured from one vernal equinox to the next; it is equal to 365 days, 5 hours, 48 minutes, 45.51 seconds. A solar year is also called an astronomical year and a tropical year.

5. ◆ A solar month is one twelfth of a solar year, totaling 30 days, 10 hours, 29 minutes, 3.8 seconds.

6. Compare sidereal time

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Example Sentences

Do we just let it fall out of sync with solar time?

From The Verge • Jul. 26, 2022

Human sleep patterns prefer to be in sync with “solar time,” he said, and standard time is closer to true solar time.

From Seattle Times • Mar. 10, 2022

With the Industrial Revolution, clock time liberated the workday from solar time and established labor routines organized by schedules — the 9-to-5 job being the ultimate expression of this.

From Washington Post • Mar. 10, 2017

Although mean solar time has the advantage of progressing at a uniform rate, it is still inconvenient for practical use because it is determined by the position of the Sun.

From Textbooks • Oct. 13, 2016

The water-clocks could show only regular, not solar, time.

From A Friend of Caesar A Tale of the Fall of the Roman Republic. Time, 50-47 B.C. by Davis, William Stearns