Year
Article
A year is a unit of time based primarily on the period of Earth's revolution around the Sun. In ordinary calendars it contains 365 days, with leap years used to keep the calendar aligned with the seasons.
Several astronomical definitions exist. The tropical year follows the seasonal cycle, the sidereal year measures Earth's orbit relative to the stars, and the anomalistic year measures the return from one perihelion to the next.
Calendar systems divide years into months, weeks, and days and use different rules for leap days or leap months. Solar, lunar, and lunisolar calendars reconcile astronomical cycles in different ways.
The term year is also used for the orbital periods of other planets and for longer recurring intervals such as the galactic year. Its exact meaning therefore depends on the astronomical or calendrical context.
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- Source / publisher: Wikipedia
- URL type: WWW
- Credits: Wikipedia
- URL: https://en.wikipedia.org/wiki/Year