Sidereal year

Article

A sidereal year is the time taken by Earth to complete one orbit around the Sun relative to the fixed stars. It is approximately 365.25636 mean solar days.

The sidereal year is slightly longer than the tropical year because Earth's rotational axis precesses, causing the equinoxes to move slowly westward along the ecliptic.

Astronomers use the sidereal year when describing orbital motion relative to an inertial reference frame. It is distinct from calendar years and from years defined by the return of the seasons.

The difference between sidereal and tropical years accumulates over long periods and is important in precise astronomy, calendar history, and the study of precession.

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• Source / publisher: Wikipedia
• URL type: WWW
• Credits: Wikipedia
• URL: https://en.wikipedia.org/wiki/Sidereal_year