Equinox

An equinox occurs twice a year when the sun is right above a point on the Equator. The equinox occurs at two specific times each year around March 20/21 and September 22/23. The name comes from Latin. Aequus (equal) and nox (night) because during the Equinox, the times of day and night are about the same. During the equinox, the sun is either at the vernal point or the autumnal point. These two points are where the celestial equator and ecliptic meet. Most people use March Equinox and September Equinox instead of Vernal Equinox and Autumnal Equinox because of the bias towards the Northern Hemisphere. There are different cultural aspects of the equinox. Nowruz or the Persian new year is held as the beginning of spring on the Vernal Equinox. In Asia, the vernal equinox and autumnal equinox mark the middle of the spring and autumn seasons. The Mid-Autumn Festival is often celebrated near the Autumnal Equinox Day which is an official holiday in Asian countries. Since the lunar calendar doesn't synchonize with the Gregorian calendar, the date could range anywhere from September to October. Earth Day was celebrated on the Vernal Equinox Day but now is celebrated in certain countries on April 22.