Happy Autumn Equinox. Sort of! Equinox means equal. Supposedly the sun is shining on the equator on this date, so the day and night are of equal duration. Actually, if you live on the equator, days are the same length year around. I wonder if all those Americans who are moving to Ecuador (watch House Hunters International if you doubt it) have considered that? Maybe they’ll miss the drama of shortening and lengthening of days…
In fact, the dates when day and night are most equal for the rest of us actually varies according to latitude, by as much as a few days. Imagine that!
But wait, there’s more! Is the Equinox the exact time that day and night are of equal length? Not really! On the Equinox, the “geographical center” of the sun is above the horizon for twelve hours, but a “day” is longer than that; after all, we count a “day” as beginning when even part of the sun is above the horizon. Furthermore, the earth refracts, or bends, the sunlight, meaning that we see light a few minutes before the sun actually rises (I guess I’d know that if I ever got up before sunrise, but….). So the Equinox is just the date that the day and night are as equal as possible.
So is this the beginning of Autumn? Well, it is the Astronomical definition of the beginning of Autumn. However, the Meteorological definition is based on temperatures and the good old Gregorian calendar, and it puts the beginning of Autumn as September 1st. Sure enough, that’s when most of us think of Autumn as beginning. It’s the time we turn the calendar page to one with a picture of red and gold leaves, it’s the time that in America we have Labor Day to signal the end of summer, and the time when (in so many countries) students return to school. All this applies to the Northern Hemisphere, of course. In Australia, in most of South America, and in a few others places, this is the first day of Spring!
(Thanks to Time and Date.com and Almanac.com (The Old Farmers’ Almanac) for all this information.)
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