First Day of Spring

What

First Day of Spring

When

3/20/2019

"The March equinox would occur on the same day every year if the Earth took exactly 365 days to make a complete revolution around the Sun. But this is not the case. It takes the Earth about 365.25 days on average to go around the Sun once. The Gregorian Calendar accounts for this by adding an extra day – the leap day – almost every 4 years. This means that each March equinox occurs about 6 hours later than the previous year's March equinox. This is why the date of the equinox can change from year to year."

"An equinox is the exact instant when the Sun is directly overhead the Equator and the Earth's rotational axis is tilted neither towards nor away from the Sun. In technical terms, this means that at the instant of the equinox, the Earth's celestial equator, which is the equator's imaginary projection into space, intersects with the center of the Sun."

"In any given calendar year, this happens twice, first around March 21 (March equinox) and then again around September 22."