Vernal Equinox

Translated literally, equinox means "equal night." Because the Sun is positioned above the equator, day and night are about equal in length all over the world during the equinoxes. A second equinox occurs each year on Sept. 22 or 23; in 2011, it will be on Sept. 23 at 5:05 A.M. EDT. This date will mark the autumnal equinox in the Northern Hemisphere and the vernal equinox in the Southern (vernal denotes "spring").

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