(CNN) — Twice a year the sun does not play a favorite. Everyone on Earth has seemingly the same status – at least when it comes to the amount of light and dark they get.
Your location on the globe also determines whether you mark the day this year on Thursday, September 22, or Friday, September 23. People in America celebrate it on Thursdays; time zone differences mean that people in Africa, Europe and Asia are marking it on their Friday.
People who are very close to the equator have about 12 hours in the day and 12 at night all year round, so they won’t notice. But hardy people close to the poles, in places like Alaska and the northern parts of Canada and Scandinavia, experience wild swings in the day-to-night ratio every year. They have long, dark winters and then summers in which the night barely penetrates.
But during equinoxes, everyone from pole to pole can enjoy a 12-hour day and night. Well, there’s only one friction — it’s not as perfectly “right” as you might have thought.
There is a good explanation (SCIENCE!) for why you don’t get precisely 12 hours of daylight on the equinox. More on that later.
But first, here are the answers to your other burning equinox questions:
Where does the word ‘equinox’ come from?
When exactly does the autumnal equinox take place?
The sun is seen heading west on Chicago’s Randolph Street just days before the fall equinox in 2019.
Terrence Antonio James/Chicago Tribune/Getty Images
For people in places like Toronto and Washington, DC, that’s 9:03 PM local time. It arrives at 8:03 p.m. in Mexico City and Chicago. West in San Diego and Vancouver, that means it arrives at 6:03 PM
But go in the other direction across the Atlantic, and the time change will bring you into Friday. For residents of Madrid, Berlin and Cairo, it is Friday at 03:03 AM. Farther east, Dubai marks the exact event at 5:03 AM
Is the Autumn Equinox the Official First Day of Fall?
Yes. Autumn officially begins on the autumnal equinox.
Allison Chinchar, CNN meteorologist, explains the differences:
“Astronomical fall is essentially the period from the autumnal equinox to the winter solstice. Those dates can vary by a day or two each year,” she says.
“Meteorological fall is different…in the sense that the dates never change and are based on climatic seasons rather than the angle of the Earth relative to the sun. These may be the seasons more people are familiar with,” he says. Chinchar.
Fall foliage can come early in high elevation places like Kenosha Pass, Colorado. This photo was taken on September 19, 2016, at night with a long exposure, lit by moonlight and passing car headlights.
RJ Sangosti/Denver Post/Getty Images
Meteorological seasons are defined as follows: March 1 to May 31 is spring; June 1 to August 31 is summer; September 1 to November 30 is fall; and from December 1 to February 28 it is winter.
“This makes some dates tricky,” Chinchar says. “For example, December 10, most people would consider winter, but if you use the astronomical calendar, that’s still technically considered fall because it falls before the winter solstice.”
She said that “meteorologists and climatologists prefer the ‘meteorological calendar’ because not only does the dates not change — making it easy to remember — but also because it’s more in line with what people think traditional seasons are.”
Why does the autumnal equinox occur in the first place?
The rising sun tries to break through the fog on the autumn equinox 2021 at the village of Glastonbury in the southwest of England.
Matt Cardy/Getty Images
The Earth rotates along an imaginary line that runs from the North Pole to the South Pole. It is called the axis, and this rotation gives us day and night.
The effect is maximum at the end of June and the end of December. Those are the solstices and they have the most extreme differences between day and night, especially near the poles. (That’s why it stays light for so long every day in the summer in places like Scandinavia and Alaska.)
But since the summer solstice three months ago in June, you’ve noticed that our days are getting shorter in the Northern Hemisphere and the nights longer. And now we are here at the autumnal equinox!
What did our ancestors know about this?
Here are just some of the locations associated with the equinox and the annual passage of the sun:
Mexico’s Chichen Itza is sacred ground during the spring and fall equinoxes.
What are some festivals, myths and rituals still with us?
All over the world, the autumnal equinox has made its way into our cultures and traditions.
Britain’s beloved harvest festivals have their roots in the autumnal equinox since pagan times.
Rikugien Gardens in Tokyo are ablaza in fall color. Autumnal Equinox is a national holiday in Japan.
thanks to Kimon Berlin
Are the Northern Lights really more active during the equinoxes?
Yes – they often put on more of a show this time of year.
It turns out that the autumnal equinox and spring (or vernal equinox) usually coincide with peak activity with the aurora borealis.
So why is the equinox not exactly equal?
It turns out that on the equinox, you actually get a little more daylight than darkness, depending on where you are on Earth. How does that happen? The answer is a bit complicated but fascinating.
The evening sun shines through the autumn-colored foliage on chestnut trees on the banks of the Landwehrkanal in Berlin’s Kreuzberg district.
Stefan Jaitner/dpa/photo alliance/AP
This deflection of light rays causes the sun to appear above the horizon when the actual position of the sun is below the horizon. The day is slightly longer at higher latitudes than at the equator because it takes longer for the sun to rise and set the closer you get to the poles.
So on the autumnal equinox, the length of the day will vary a bit depending on where you are. Here are a few breakdowns to give you an approximate idea:
• At or near the equator: approximately 12 hours and 6 minutes (Quito, Ecuador; Nairobi, Kenya and Singapore)
• At or near latitude 30 degrees north: approximately 12 hours and 8 minutes (New Orleans, Louisiana; Cairo, Egypt; and Shanghai, China)
• At or near latitude 60 degrees north: approximately 12 hours and 16 minutes (Helsinki, Finland and Anchorage, Alaska)