March 20, 2015 is the first day of spring for the Northern Hemisphere. Google is celebrating the vernal equinox with a Google Doodle.
The first day of spring is also known as the spring equinox, or the vernal equinox. The spring equinox is one of the two annual equinoxes where the sun shines directly on the equator and the length of day and night is nearly the same. “Vernal” means “of relating to spring” in Latin.