Great Year

Article

The Great Year is a term used for a very long astronomical or cosmological cycle. In astronomy it most commonly refers to the period of Earth's axial precession, during which the equinoxes complete a circuit relative to the background stars.

The precessional Great Year lasts about 25,700 years. Over this interval the direction of Earth's rotational axis traces a circle in the sky and the identity of the pole star changes.

Ancient Greek, Indian, Persian, and later philosophical traditions also used the idea of a Great Year for a complete recurrence of celestial configurations or a vast cycle of cosmic renewal. The length assigned to it varied greatly among traditions.

The astronomical use is based on measurable precession, whereas broader cosmological uses are historical or philosophical concepts. The term therefore has different meanings depending on context.

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