Ah, the old Autumnal Equinox

Fall arrived Tuesday evening, so we are told. The orbit and tilt of the earth is not a thing that matches perfectly with our calendars, so this time it landed on September 22, which is actually more common than the 21st.

If you want just a touch of science (I know you do), what’s happening is that the tilt of the earth, as it swings in its orbit around the sun, is such that the sun is crossing the equator around September 22 (directly overhead there at noon). Unfortunately for us, it’s on its way down south of that, eventually to over the imaginary line from our school globes called the Tropic of Capricorn. It reaches there about December 21, when we in the northern hemisphere enjoy our shortest day of the year. You remember that: getting dark at four in the afternoon, no light in the morning until almost eight o’clock.

Tuesday was called the Fall Equinox or the “Autumnal Equinox” if we want to be even more verbose— meaning “equal night”, but it’s really meaning equal day and night.

I once spent a year in Resolute Bay, up on the arctic islands, as a weather observer in what now seems like a previous life. Like down here, September 22 is the usual “equinox” in Resolute, with equal day and night, but the sun is at such a low angle there that in the winter it can’t get over the horizon at all (I’ll keep referring to the sun doing something, which we humans have done since the beginning of time, though it’s us who are really doing most of the moving). In the summer, it manages to shine at a low angle right over the North Pole, such that it’s seen all day. I lived in the “Land of the Midnight Sun”.
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