Traditionally, March 21 has always been considered the first day of Spring. Now astronomers and calendar manufacturers set March 20 for the season start.
That little fact had me chasing down the rabbit hole to find out why. What I learned was a surprise.
Why the change?
If you’re not into astronomy, the answer is a bit complicated determined by the direct rays of the Sun shining down on the equator and producing the effect of equal day and night. The cycle repeats as the earth completes its rotation around the sun. Never going further than the Tropic of Cancer in the north and Tropic of Capricorn in the southern hemisphere.
What causes the date to move?
Seasons are defined as beginning at strict 90-degree intervals, these positional changes affect the time the earth reaches each 90-degree location in its orbit around the sun. But that isn’t a stable position.
- Our years have a varying number of days which means the dates shift.
- Add the Earth’s elliptical orbit that causes a variation in the strict 90-degree position and the pull of gravity from the other planets on the position of the Earth’s orbit.
- Days and nights are never actually equal. The Farmer’s Almanac charts show that daylight is technically longer by several minutes due to the atmosphere of the earth.
The BIG surprise…Springs are getting shorter.
According to The Farmer’s Almanac current season lengths for the Northern Hemisphere are:
Summer — 93.641 days
Autumn — 89.834 days
Winter — 88.994 days
Spring — 92.771 days
Spring is currently being reduced by approximately one minute per year and winter by about one-half a minute per year.
Summer gains the minute lost from spring, and autumn gains the half a minute lost from winter.
That was a disappointing fact I hadn’t expected because I’m not a big fan of hot weather. An extra minute of summer is not a good thing for me.
Knowing I’m losing the beauty of Springtime weather does make me want to enjoy every second of this Spring.