The vernal equinox, referred to by most as the first day of spring, occurred at 1:14 a.m. this morning. The equinox happens at the point when the sun crosses the celestial equator from South to North, and arrived earlier this year (March 20 instead of March 21) because it's a leap year. With the beauty of this early spring comes dreaded seasonal allergies, encouraged by the mild winter and balmy temperatures.