FIRST DAY OF SPRING: VERNAL EQUINOX

Spring begins in the Northern Hemisphere on March 20, 2012. Spring! This season brings increasing daylight, warming temperatures, and the rebirth of flora and fauna.

The word equinox is derived from the Latin words meaning "equal night." The spring and fall equinoxes are the only dates with equal daylight and dark as the Sun crosses the celestial equator. The tilt of Earth is zero. WIth no tilt, the North/South Poles are basically straight up and down.

source: www.almanac.com