Spring officially arrived at 6:28 Monday morning. The day is formally known as the vernal equinox. What is the vernal equinox? The word “equinox” means the point at which the sun crosses the Earth’s equator. On this day, the sun shines directly on the equator, This happens on March 19, 20 or 21 every year. The start of Spring is one of two equinoxes to happen each year.