Of all the big four seasonal dates - the winter and summer solstices and the spring and fall equinoxes - the fall equinox falls under “Most Ignored.”

Winter solstice, the shortest day of the year, is famed throughout the world in nearly every culture and is celebrated in a wide variety of festivals. Summer solstice is the longest day of the year, marking our first day of summer, a high holiday for most American school kids. The spring equinox denotes for many the end of winter, and the beginning of both new life, and the allergy season.

But most of us pass right by the fall - or autumnal - equinox with nary a notice. So our column this week is dedicated to this unsung seasonal date that we will celebrate on the 22nd. It’s time the equinox got equal time.

So what is this fall equinox all about anyway?

Our planet, as you learned in school many years ago, travels around the sun in a nearly circular orbit. And we all know that the Earth spins with a slight tilt to it.

Well, we spin about smoothly enough on our axis each day, almost like the perfect top, and revolve slowly and effortlessly around the sun year after year. But what confuses some people is that our planet always has its spin axis pointing in the same direction – all year long. For us in the northern hemisphere, our pivot point points towards Polaris, aka The North Star.

At winter solstice we in the northern hemisphere are tilted away from the sun. Therefore, we have shorter days and cooler temps, and the sun hangs low in the sky.

The summer solstice is when we are tilted most toward the sun and it starts to get noticeably hot and the daytime is longest.

But right between those two days, once in March and once six months later in September, we are tilted neither towards nor away from Sol.

The September date is this Thursday. Since we are not tilted with respect to the sun, our “daytime” will have 12 hours with the sun being above the horizon, and 12 hours when it will be below. Hence the term equinox, from the Latin æquinoctium, from “æqui” meaning equal, and “nox” meaning night, inferring equal times of day and night.

Because the earth is standing at virtual attention to the sun, there will be light from pole to shining pole. That means essentially everyone on this planet will get 12 hours of sun up, 12 hours of sundown. It is an equal opportunity day.

But the equinox is more than just 12 up, 12 down.

The sun on this day rises due east and sets due west for everyone. And I mean the real east and the real west! None of that funky compass stuff.

The compass faces toward a magnetic North Pole, which is not true north for just about everyone on Earth. Thus, neither is the “E” of the compass true east, nor its “W” true west.

But on the day of the equinox, if you have a nice flat horizon you can mark true east and true west truer than any compass by observing exactly where the sun rises and sets.

Now I sort of didn’t tell the whole truth when I told you that all people on earth would get 12 hours of sun up, and 12 hours of no sun. There are two places that are exempted here. Can you guess what those places might be?

I’ll give you a hint. At the equator, one will see the sun rise due east, travel straight up over head then straight down, and set due west.

Here in southern California we will see it rise due east at an angle, sweep over the southern skies at noon (only about 57 degrees above horizon at its height), and set at a sharp angle due west.

Higher north in Canada the sun rises due east, and sharply cuts through the low southern skies, setting 12 hours later due west.
Any ideas yet of where the sun neither rises nor sets on this day?

At the poles. At the North and South poles, the sun will not rise or set! One standing there will actually see the sun just skirt the horizon in a giant circle, never rising nor setting.

For us who live here in southern California it would be a quite a strange sight indeed!

Here are some things you can do Thursday.

In the morning you can mentally mark the place on the horizon where the sun rises (assuming no hills!) and truly call that East. Twelve hours later you can see where it sets, again assuming a flat horizon, and mark that as West.

Then watch in the next weeks as we head toward the next seasonal marker, the winter solstice, how the sun rises more southerly, moves lower through the sky, and sets more southerly. All this means less sunlight, lower temperatures, a lower sun, and more annoying sun-in-the-eyes on your drive to work.

Have an awesome equinox!