Sidereal year

A sidereal year, or sidereal year ( to Latin sidus, genitive sideris Star ') is the time that passes, seen from the Earth to the sun occupies the same position in the sky in relation to a fictitious infinitely distant fixed stars without proper motion.

Explanation

The sidereal year thus represents the time for one orbit of the Earth around the Sun with respect to a fixed direction in space, as they can be determined from the sky position of the sun. So this is a complete revolution of 360 ° around the sun in a fixed fundamental system.

Duration / length

The sidereal year lasts 31,558,149.54 seconds, which corresponds to (epoch J2000.0 )

Respectively

The sidereal year is 20 minutes and 24 seconds longer than the tropical year, which forms the basis for the civil year of the calendar calculations.

The difference between sidereal and tropical year is based on the precession of the equinox, which is caused by the precession of the Earth's axis with a period of about 25,800 years ( precession ).

So a sidereal year is about tropical years.

Impact / relevance

In everyday life and on the life expectancy of a person with respect to the difference between the sidereal and tropical years is negligible. For many centuries, it manifests itself by shifting the Ekliptiksternbilder.