With the passing of the autumnal equinox yesterday, the calendar officially turns from Summer to Fall, as is customary this time of year. And so even as we continue to perspire we begin to consider, faintly, the possibility, of open windows, long sleeves, and–dare we think it–sweaters and jackets.
On the strength of a cold winter followed by epic spring rainfall, experts and common folk alike had predicted a mild summer. But the climate gods had other ideas, so the summer that was supposed to happen did not. The rains, so generous in late spring, came to an abrupt halt, as though the tap had simply been turned off, and there followed many unbroken weeks of unrelenting, historic dry, which have yet to end as of this writing. By August the gains of spring had been all but erased, and we were once again fully in the grip of drought. The parched earth baked under a withering sun, and the mercury soared above a hundred for days on end.
The turn was late this year. As everyone knows, Autumn begins every year on September 21. Except that it doesn’t. Tugged this way and that by countless tendrils of gravity both slender and stout reaching to the stars and beyond, the Earth never traces twice exactly the same path in its journey about the sun. Our planet also wobbles a bit as it rotates. And so the sun stands exactly vertically above the Earth’s equator at a different measured moment every seasonal cycle. And there is something of a paradox in this because our calendars and our clocks both derive from the sun’s apparent motion, whose stubborn imprecision has caused no end of vexation for those wishing to keep close track of this thing we call “time.”
The solar zenith will cross the planet’s midline again, of course, in six months give or take a few hours, tracking in the other direction as it shuttles endlessly between twenty three point five north latitude and twenty three point five south. And as this reliable solar cycle defines the seasons, it also defines in ways both large and small the rhythms of life for this planet’s inhabitants.
Our eyes and our experience tell us that the sun moves while we stand still. It “rises” and “sets.” It crosses the sky daily, moving steadily and unerringly from one horizon to the other, always east to west. It moves yearly, climbing over the months to its apex, pausing briefly, receding to its nadir, and pausing again. But all of this motion is an illusion, albeit a very good one. Because by the implacable logic of Occam’s Razor, it is the smaller body, the Earth, that moves, and the larger, the Sun, that does not.
Illusory or not, from the human viewpoint, these cycles are themselves invariant and forever, reassuring absolutes in a world full of relative. Except that they aren’t. In the same way as a spinning top, the Earth’s rotational axis traces a wobbly circle–“precesses” in the argot of physics–completing a circuit every twenty-two thousand years or so. The change caused by this motion occurs slowly enough that it would take a half-dozen normal lifetimes laid end-to-end to even begin to notice. Nevertheless, in eleven thousand years, give or take, any humans still around will be celebrating the beginning of Fall in March. But in another eleven thousand, again give or take, this season will once again arrive at the “right” time, in the last quarter of September.
Even the familiar twenty-four hour day is a temporary arrangement. The tight gravitational bond of Earth and Moon act as a brake on the rotation of both. A billion years ago our planet spun much faster than now, completing three or four rotations in the same length of time now required to complete just one. Over the next billion or so it will continue to slow, gradually winding down until it and the moon are locked in a synchronous embrace. The moon, being a much smaller body, fulfilled its end of the deal long ago, so that from our viewpoint it has a bright side, familiar to us from its “full” phase, and a dark side, which we never, ever see fully illuminated.
Here at latitude thirty degrees, seasonal change is a subtle affair. This far south, not all that far from the tropics, the warm season dominates, lasting some years from late April to early October. And as if reluctant to depart, is almost always slow to release its grip. But change is happening, and if you pay attention, the signs of it are legion.
Well off the vertical now, the midday sun, still hot, is no longer painfully so. The mornings have lost their former enervating heaviness, and while not exactly crisp yet, are beginning to hint in that direction. The days grow rapidly shorter; today we will have two minutes less daylight than yesterday and tomorrow we will have two minutes less than today. The light now has a slanting, golden quality to it unique to this time of year. Cicadas, white noise makers of summer, have ceased their endless hypnotic droning, having either mated or died trying. Pecans and acorns are ripening, and here and there a few outliers have already fallen. Squirrels, foraging with a manic energy, are visibly putting on weight.
If Summer is a brass marching band, big and bright, loud and glorious, then Fall is a solitary woodwind: wistful with a hint of melancholy, yet so beautiful it breaks your heart. The word itself, “autumnal,” in three short syllables captures almost perfectly the piercing ambiguity of the human condition.
With the arrival of Fall we welcome and celebrate the change, revel in the colorful turning of the leaves, enjoy the rediscovered, nearly forgotten pleasure of cool air on flesh. Without quite realizing why, our step quickens and we scurry about with renewed and welcome vigor. Yet beneath it all is an insistent and vaguely troubling sense of loss, which darkens what ought to be be a time of joy. And we are not sure why.
And then we remember. We remember that Autumn is the time of slow dying, the withering away of fullness and plenty, light and life. And as the light leaves us and Winter draws near, that ancient primordial awareness, older than our species, is reawakened. Suddenly, somehow we know, without even being told, that it is time to gather, time to reap, time to prepare. Because darkness soon falls.