tropical year definition of tropical year in the Free Online Encyclopedia.

tropical year, time between successive vernal equinoxes equinox (ē`kwĭnŏks), either of two points on the celestial sphere where the ecliptic and the celestial equator intersect.
..... Click the link for more information. ; 365 days, 5 hr, 48 min, 46 sec of mean solar time (see solar time solar time, time defined by the position of the sun. The solar day is the time it takes for the sun to return to the same meridian in the sky. Local solar time is measured by a sundial .
..... Click the link for more information. ). The tropical year is the basis of the year year, time required for the earth to complete one orbit about the sun. The solar or tropical year is measured relative to the sun and is equal to 365 days, 5 hr, 48 min, 46 sec of mean solar time (see solar time ).
..... Click the link for more information. used in the Gregorian calendar calendar [Lat., from Kalends], system of reckoning time for the practical purpose of recording past events and calculating dates for future plans. The calendar is based on noting ordinary and easily observable natural events, the cycle of the sun through the seasons
..... Click the link for more information. .

tropical year [′träp·ə·kəl ′yir]

(astronomy)

A unit of time equal to the period of one revolution of the earth about the sun measured between successive vernal equinoxes; it is 365.2422 mean solar days or 365 days 5 hours 48 minutes 46 seconds. Also known as astronomical year.