Year

A year (from Old English gēar) is the orbital period of the Earth moving around the Sun. For an observer on the Earth, this corresponds to the period it takes the Sun to complete one course throughout the zodiac along the ecliptic.

In astronomy, the Julian year is a unit of time, defined as 365.25 days of 86400 SI seconds each (no leap seconds).

There is no universally accepted symbol for the year as a unit of time. The International System of Units does not propose one. A common abbreviation in international use is a (for Latin annus), in English also y or yr.

Due to the Earth's axial tilt, the course of a year sees the passing of the seasons, marked by changes in weather, hours of daylight, and consequently vegetation and fertility. In temperate and subpolar regions, generally four seasons are recognized: spring, summer, autumn and winter, astronomically marked by the Sun reaching the points of equinox and solstice, although the climatic seasons lag behind their astronomical markers. In some tropical and subtropical regions it is more common to speak of the rainy (or wet, or monsoon) season versus the dry season.

A calendar year is an approximation of the Earth's orbital period in a given calendar. A calendar year in the Gregorian calendar (as well as in the Julian calendar) has either 365 (common years) or 366 (leap years) days.

The word "year" is also used of periods loosely associated but not strictly identical with either the astronomical or the calendar year, such as the seasonal year, the fiscal year or the academic year, etc. By extension, the term year can mean the orbital period of any planet: for example, a "Martian year" is the time in which Mars completes its own orbit. The term is also applied more broadly to any long period or cycle, such as the "Great Year".

Read more about Year:  Etymology, Seasonal Year, Calendar Year, Symbol

Famous quotes containing the word year:

    Mothers are not the nameless, faceless stereotypes who appear once a year on a greeting card with their virtues set to prose, but women who have been dealt a hand for life and play each card one at a time the best way they know how. No mother is all good or all bad, all laughing or all serious, all loving or all angry. Ambivalence rushes through their veins.
    Erma Bombeck (20th century)

    We are often made to feel that there is another youth and age than that which is measured from the year of our natural birth. Some thoughts always find us young, and keep us so. Such a thought is the love of the universal and eternal beauty.
    Ralph Waldo Emerson (1803–1882)

    In certain savage tribes in New Guinea, they put the old people up in the trees and shake them once a year in the spring; if they don’t fall out they let them live another year.
    John Dos Passos (1896–1970)