Does autumn really start on the equinox?

Here’s the equinox sunrise over Havens Corner Road in Penn Yan on September 22, 2020.
09/22/2022
Story and photos by Derek Doeffinger

It’s very possible we’ve been misled about the start of autumn all our lives. Today is supposed to be the first day of autumn as signaled by the arrival of the autumnal equinox at 9:04 p.m. But is it? You see there’s a problem. Maybe one even as controversial as to whether Pluto is a planet or not.

So should you hold your first day of autumn party tonight or not? Let’s find out.

We all know the start of autumn is supposed to correspond with the equinox. But there’s a competitor who has snuck in and is saying “Wait a second.” Or in reality, let’s wait a couple of days. The controversy threatens to blow up decades of televised meteorological assurances that autumn starts with the equinox.

What’s the problem? For years, weather forecasters have assured us that autumn starts when the length of the day is the same as the length of the night. That’s the tipping point for when darkness starts to exceed lightness. They’ve told us that day is the equinox.

But it seems they’re mistaken. Sort of. For example, on today, the proclaimed equinox date (Thursday September 22, 2022), in Geneva, the sun rises at 6:55 a.m. and sets at 7:05 p.m. What the heck? That’s a ten minute difference, meaning the day clearly lasts longer than the night. What’s an equinox celebrant to do?

Waiting for the Fairport boat parade on the last summer weekend, the Wowk ladies said they’d check out the equinox article.

It seems there’s only one choice. Join the equilux club. The equilux (Latin for equal light) occurs when the designated hours of sunrise and sunset are almost exactly twelve hours apart, so there’s twelve hours of daylight and twelve of night.

But the equinox (Latin for equal night) doesn’t use sunrise and sunset times. It uses an astronomical measurement based on when the exact center of the sun crosses the Earth’s equator.

That causes a discrepancy because the calculation doesn’t quite jive with how we determine sunrise and sunset times. Both sunrise and sunset punch the clock when the top edge of the sun touches the horizon. Using sunrise/sunset times pushes those equal days and nights out until Sunday the 25th..

Got that? If you do, then you’re enlightened; if you don’t, then you’re endarkened (and welcome to my world).

Just know that it’s Sunday the 25th when based on the traditional calculations for sunrise and sunset times that the day is twelve hours long and the night is twelve hours long. The equilux.

Don’t get it? Go to www.timeanddate.com/astronomy/equilux.html to learn more.

 


Derek Doeffinger spent a few decades at Kodak explaining how people can take better pictures and then encouraging them to use Kodak products — especially digital cameras. That last part didn’t quite work out. Fortunately during his Kodak days he became an obsessed outdoor photographer, especially of Finger Lakes waterfalls. He’s written several photos books about the Finger Lakes and digital photography, and now has written quite a few articles for Life in the Finger Lakes.

1 Comment

  • Rick Kornbau says:

    Fascinating article ! Thank you for enlightening us ! It would seem that the method of determining the equiNOX’s occurrence is more precise, repeatable and reproducible than that for the equiLUX. So all is well !

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