tropical year

tropical year (plural tropical years)

1. The time that it takes for the Sun to return to the same position along the ecliptic, as viewed from the Earth, especially, completing a full cycle of seasons.
2. (in particular) A vernal equinox year; the time between two successive vernal equinoxes.
3. (by extension) The time it takes for any astronomical object (such as a planet, dwarf planet, small Solar System body, or comet) in direct orbit around a star (such as the Sun) to make one revolution around the star, taking into account orbital precession.

The vernal equinox tropical year of about 365.2424 days (varying over the centuries) is used for the Gregorian as well as earlier calendars, to keep the vernal equinox as close as possible to March 21st. This is different from the mean tropical year of 365.24219 days.

• solar year; astronomical year, equinoctial year, Sothic year (inexact)

• mean tropical year

• tropical month

• sidereal year