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First day of fall: Why the equinox isn’t as equal as you might think

September 22, 2022
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(CNN) — The sun plays no favorites twice a year. Everyone on Earth seems to have the same status – at least as far as the amount of light and dark they get.

We have entered our second and final equinox of 2022. If you live in the Northern Hemisphere, you know it as the Autumnal Equinox (or Autumnal Equinox). For people south of the equator, this equinox actually signals the coming of spring.

Your location on the globe also determines whether you commemorate the day on Thursday September 22nd or Friday September 23rd this year. The people of America celebrate it on Thursday; Time zone differences mean that people in Africa, Europe and Asia will celebrate it on their Friday.

People who are very close to the equator have roughly 12-hour days and 12-hour nights year-round, so they don’t really notice anything. But hardy folk near the poles, in places like Alaska and the northern parts of Canada and Scandinavia, experience wild swings in the day-night ratio every year. They have long, dark winters and then summers, when night scarcely penetrates.

But during the equinox, everyone can enjoy a 12-hour division of day and night from pole to pole. Well, there’s just one friction – it’s not as completely “same” as you might have thought.

There’s a good explanation (SCIENCE!) as to why you’re not getting it I agree 12 hours of daylight on the equinox. More on that below.

But first, here are the answers to your other burning equinox questions:

Where does the word “equinox” come from?

From our CNN Fast Facts file: The term equinox comes from the Latin word equinoxium, meaning “equality between day and night.”

When exactly does the autumnal equinox occur?

The setting sun looks west on Randolph Street in Chicago just days before the 2019 autumn equinox.

The setting sun looks west on Randolph Street in Chicago just days before the 2019 autumn equinox.

Terrence Antonio James/Chicago Tribune/Getty Images

For people in places like Toronto and Washington, DC, that’s 9:03 p.m. local time. It arrives at 8:03 p.m. in Mexico City and Chicago. Out West in San Diego and Vancouver, meaning it arrives at 6:03 p.m

But go the other way across the Atlantic and the time change puts you on Friday. For residents of Madrid, Berlin and Cairo, it arrives at 3:03 a.m. on Friday. Further east, Dubai marks the exact event at 5:03 am

For Bangkok residents, it is 8:03 AM, while Tokyo arrives at 10:03 AM. You can click here to see more cities (rounded down by one minute and adjusted for daylight saving time).

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Is the Autumnal Equinox the Official First Day of Autumn?

Yes. Autumn officially begins with the Autumnal Equinox.

But actually there are two units of measurement for the seasons: “the astronomical seasons” (which follow the arrival of equinoxes and solstices) and the so-called “meteorological seasons”.

Allison Chinchar, CNN meteorologist, explains the differences:

“The astronomical autumn is essentially the period from the autumnal equinox to the winter solstice. These dates can vary by a day or two each year,” she says.

“The meteorological fall is different…in that the dates never change and are based on climatological seasons rather than the Earth’s angle to the Sun. These are perhaps the seasons that more people are familiar with,” says Chinchar.

Fall foliage can appear early in high elevation locations like Kenosha Pass, Colorado. This photo was taken on September 19, 2016 at night with a long exposure, illuminated by moonlight and passing car headlights.

Fall foliage can appear early in high elevation locations like Kenosha Pass, Colorado. This photo was taken on September 19, 2016 at night with a long exposure, illuminated 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 1st to August 31st is summer; September 1st to November 30th is fall; and from December 1st to February 28th is winter.

“That makes some dates difficult,” says Chinchar. “For example, most people would consider December 10th to be winter, but if you use the astronomical calendar, that still technically counts as autumn because it predates the winter solstice.”

She said that “Meteorologists and climatologists prefer to use the ‘meteorological calendar’ because not only do the dates not change — making it easy to remember — but also because it’s more consistent with what.” people think they are traditional seasons.”

Why does the Autumnal Equinox happen at all?

The rising sun attempts to break through the mist near the town of Glastonbury in south-west England on the 2021 Autumn Equinox.

The rising sun attempts to break through the mist near the town of Glastonbury in south-west England on the 2021 Autumn Equinox.

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.

However, the axis tilts 23.5 degrees, as NASA explains. This enables one hemisphere of the planet to receive more sunlight than the other during half of the year’s orbit around the sun. This discrepancy in sunlight is what triggers the seasons.

The effect is greatest in late June and late December. These are the solstices, and they have the most extreme differences between day and night, especially near the poles. (This is why it stays light so long each day in summer in places like Scandinavia and Alaska.)

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But since the summer solstice three months ago in June, you’ve noticed that our northern hemisphere days have been getting shorter and nights longer. And now here we are at the Autumnal Equinox!

What did our ancestors know about all this?

Long before the age of clocks, satellites, and modern technology, our ancient ancestors knew a great deal about the movement of the sun across the sky—enough to build massive monuments and temples that, among other things, served as giant calendars to mark the seasons.

Here are just a few of the places associated with the equinox and annual transit of the sun:

• Megalithic Temples of Malta: Some of the earliest free-standing stone structures in the world, these seven temples on the Mediterranean island were built between 5,000 and 6,000 years ago. At the Hagar Qim and Mnajdra temples, the semi-circular chambers are oriented to frame the rising sun at an equinox between the stones.
Chichen Itza

Mexico’s Chichen Itza is sacred ground during the spring and fall equinoxes.

Getty Images/zxvisua

• Chichén Itzá (Yucatán Peninsula, Mexico): El Castillo, the famous pyramid of Chichén Itzá, puts on an impressive show on the equinoxes. Constructed between 1050 and 1300 by the Toltec Maya people, the pyramid was built to cast a shadow on the north balustrade of El Castillo during the equinox. It takes the form of a snake slithering down the stairs, and the ancient special effect is enhanced by the heads of chiseled beasts at the base.
• Jantar Mantar (New Delhi, India): These late Mughal buildings are of much more recent origin (1724 and 1730) and serve as astronomical observatories.

Which festivals, myths and rituals still accompany us?

All over the world, the autumnal equinox has become ingrained in our cultures and traditions.

In Greek mythology, the autumnal equinox marks the return of the goddess Persephone to the underworld for three months, where she is reunited with her husband Hades.
Chinese and Vietnamese still celebrate the Harvest Moon (aka the Mid-Autumn Festival). Lanterns line the streets as people give thanks, watch the moon, and eat. Round pastries called mooncakes are a Mid-Autumn Festival favorite. It takes place on the 15th day of the eighth lunar month of the Chinese calendar. In 2022 it fell on September 10th.

Britain’s popular harvest festivals have their roots in the autumnal equinox since pagan times.

Rikugien, Tokyo Autumn leaves

Tokyo’s Rikugien Gardens are ablaze with vibrant fall colors. Autumn Equinox is a national holiday in Japan.

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Courtesy of Kimon Berlin

Are the Northern Lights really more active at the equinoxes?

Yes – they often put on more of a show this time of year.

It turns out that the autumn and spring equinoxes (or vernal equinoxes) usually coincide with peak Aurora Borealis activity.

Why isn’t the equinox exactly the same?

It turns out that there is actually slightly more daylight than darkness on the equinox, depending on where you are on the planet. How does this happen? The answer is a bit complicated, but fascinating.

As the US National Weather Service explains, the “nearly” equal hours of day and night are due to the complex way a sunrise is measured and the refraction of sunlight in our atmosphere.
The evening sun shines through the autumn-colored foliage of the chestnut trees on the banks of the Landwehr Canal in Berlin-Kreuzberg.

The evening sun shines through the autumn-colored foliage of the chestnut trees on the banks of the Landwehr Canal in Berlin-Kreuzberg.

Stefan Jaitner/dpa/picture-alliance/AP

This bending of the light rays causes the sun to appear above the horizon when the actual position of the sun is below the horizon. Days are slightly longer at higher latitudes than at the equator because the sun rises and sets longer the closer you get to the poles.

On the autumnal equinox, day length varies a bit depending on where you are. Here are a few breakdowns to give you a rough idea:

• At or near the equator: Approximately 12 hours and 6 minutes (Quito, Ecuador; Nairobi, Kenya; and Singapore)

• At or near 30 degrees north latitude: 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)

For a truly equal day/night split, you’ll have to wait days or even weeks after the official equinox. This day is called Equilux, and when it occurs depends on your latitude.



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