“equation of time”的概念、定义、翻译、参考文献-科学参考

equation of time

Physics

The length of time that must be added to the mean solar time, as shown on a clock, to give the apparent solar time, as shown by a sundial. The amount varies during the year, being a minimum of −14.2 minutes in February and a maximum of +16.4 minutes in October. It is zero on four days (April 15/16, June 14/15, Sept. 1/2, Dec. 25/26). The difference arises as a result of two factors: the eccentricity of the earth’s orbit and the inclination of the ecliptic to the celestial equator.

Astronomy

The difference between apparent solar time and mean solar time; technically, the difference between the hour angle of the true Sun and that of the fictitious mean sun. Whereas the mean sun by definition proceeds uniformly, the true Sun may be some minutes ahead of or behind its expected position because of the eccentricity of the Earth’s orbit. Moreover, the true Sun moves along the ecliptic, not the celestial equator, which is an additional contributor to the equation of time. The difference reaches a maximum in early November, when apparent solar time is over 16 min ahead of mean solar time, and in mid-February, when apparent solar time is over 14 min behind mean solar time. The equation of time is zero on four occasions during the year: on April 15, June 14, September 1, and December 25.

单词	equation of time
释义	equation of time Physics The length of time that must be added to the mean solar time, as shown on a clock, to give the apparent solar time, as shown by a sundial. The amount varies during the year, being a minimum of −14.2 minutes in February and a maximum of +16.4 minutes in October. It is zero on four days (April 15/16, June 14/15, Sept. 1/2, Dec. 25/26). The difference arises as a result of two factors: the eccentricity of the earth’s orbit and the inclination of the ecliptic to the celestial equator. Astronomy The difference between apparent solar time and mean solar time; technically, the difference between the hour angle of the true Sun and that of the fictitious mean sun. Whereas the mean sun by definition proceeds uniformly, the true Sun may be some minutes ahead of or behind its expected position because of the eccentricity of the Earth’s orbit. Moreover, the true Sun moves along the ecliptic, not the celestial equator, which is an additional contributor to the equation of time. The difference reaches a maximum in early November, when apparent solar time is over 16 min ahead of mean solar time, and in mid-February, when apparent solar time is over 14 min behind mean solar time. The equation of time is zero on four occasions during the year: on April 15, June 14, September 1, and December 25.
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