▷ First Day Of Autumn: Why The Equinox Is Not As Equal As You Might Think

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(CNN) – Twice a year, the sun does not play as a favorite. Everyone on Earth is apparently in the same state, at least in terms of how much light and darkness they get.

We have entered our second and final equinox of 2022. If you reside 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 arrival of spring.

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

People very close to the equator have roughly 12 hours of day and 12 hours of night all year round, so they won’t really notice a thing. But hardy people near the poles, in places like Alaska and northern parts of Canada and Scandinavia, experience wild changes in the day/night ratio every year. They have long, dark winters, and then summers where night barely comes.

But during the equinoxes, everyone from pole to pole enjoys a 12-hour division of day and night. Well, there’s just one rub: It’s not as perfectly “equal” as you might have thought.

There’s a good (SCIENCE!) explanation for why you’re not getting it precisely 12 hours of daylight at the equinox. More on that below.

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

Where does the word “equinox” come from?

From our CNN Fast Data File: The term equinox comes from the Latin word equinox, meaning “equal between day and night.”

Exactly when does the autumnal equinox occur?

The setting sun is seen looking west on Randolph Street in Chicago just days before the 2019 fall equinox.

Terrence Antonio James/Chicago Tribune/Getty Images

For people in places like Toronto and Washington, DC, it’s 9:03 PM local time. It arrives at 20:03 in Mexico City and Chicago. West of San Diego and Vancouver, that means it arrives at 6:03 p.m

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

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

Is the autumnal equinox the first official day of autumn?

yes Fall officially begins at the autumnal equinox.

But there are actually two measurements of the seasons: “astronomical seasons” (which follow the arrival of the equinoxes and solstices) and what are called “meteorological seasons”.

CNN meteorologist Allison Chinchar explains the differences:

“Astronomical autumn is essentially the time period from the fall equinox to the winter solstice. These dates can vary by a day or two each year,” he says.

“Meteor fall is different…as the dates never change and are based on the weather seasons rather than the Earth’s angle to the sun. Perhaps these are the seasons most people are familiar with.” says Chinchar.

Fall foliage can arrive 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 the moonlight and the headlights of passing cars.

RJ Sangosti/Denver Post/Getty Images

The weather seasons are defined as follows: from March 1 to May 31 is spring; From June 1 to August 31 is summer; From September 1 to November 30 is autumn; and from December 1 to February 28 is winter.

“That makes some dating tricky,” says Chinchar. “For example, December 10 is what most people would consider winter, but if you use the astronomical calendar, it’s still technically fall because it’s before the winter solstice.”

He said that “meteorologists and climatologists prefer to use the ‘weather calendar’ because not only do the dates not change — which is easy to remember — but also because it is more in line with what people think of as the traditional seasons “.

Why does the autumnal equinox occur in the first place?

The rising sun tries to break through the fog near the town of Glastonbury in southwest England on the 2021 autumn equinox.

Matt Cardy/Getty Images

The Earth rotates along an imaginary line that goes from the North Pole to the South Pole. It’s called the axis, and this rotation is what gives us day and night.

However, the axis is tilted at 23.5 degrees, as explained by NASA. This positions 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 maximum at the end of June and the end of December. These are the solstices, and have the most extreme differences between day and night, especially near the poles. (This is why the light stays on for so long each day during the summer in places like Scandinavia and Alaska.)

But since the summer solstice three months ago in June, you’ve noticed that our days have been getting progressively shorter in the northern hemisphere and our nights longer. And now 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 lot about the sun’s movement across the sky, enough to build massive monuments and temples that, among other purposes, served as giant calendars to mark the seasons. .

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

• Megalithic Temples of Malta: These seven temples on the Mediterranean island are some of the earliest free-standing stone buildings in the world, dating back 5,000 to 6,000 years. In the temples of Hagar Qim and Mnajdra, the semicircular chambers are aligned so that the rising sun at an equinox is framed between the stones.

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

Getty Images/zxvisua

• Chichén Itzá (Yucatan Peninsula, Mexico): El Castillo, the famous pyramid of Chichén Itzá, offers a shocking show on the equinoxes. Built by the Toltec-Mayan people between 1050 and 1300, the pyramid was built to shade the north balustrade of El Castillo during the equinoxes. It looks like the shape of a snake slithering down the stairs, and the ancient special effect is accentuated by the carved beast heads at the base.

• Jantar Mantar (New Delhi, India): Of much more recent origin (1724 and 1730), these buildings from the late Mughal period are astronomical observatories.

Which festivals, myths and rituals are still with us?

All over the world, the autumnal equinox has woven its way into 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.

The Chinese and Vietnamese still celebrate the Harvest Moon (also known as the Mid-Autumn Festival). Lanterns line the streets as people give thanks, look at the moon and eat. Round cakes called moon cakes are a Mid-Autumn Festival favorite. It is celebrated on the 15th day of the eighth lunar month of the Chinese calendar. In 2022, it fell on September 10.

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

Tokyo’s Rikugien Gardens are in autumn color. The Autumnal Equinox is a national holiday in Japan.

courtesy of Kimon Berlin

Are the northern lights really most active at the equinoxes?

Yes, they often do more than one show this time of year.

It turns out that the autumnal and vernal equinox (or vernal equinox) usually coincide with peak activity with the aurora borealis.

So why isn’t the equinox exactly the same?

It turns out that you actually get a little more daylight than darkness at 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 “almost” equal hours of day and night are due to the complex way in which 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’s Kreuzberg district.

Stefan Jaitner/dpa/picture-alliance/AP

This bending of light rays causes the sun to appear above the horizon when the sun’s actual position is below the horizon. The day is slightly longer at higher latitudes than at the equator because the sun takes longer to rise and set the closer you get to the poles.

So at the autumnal equinox, the length of the day will vary a bit depending on where you are. Here are a few broken down to give you a rough idea:

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

• At or near 30 degrees north latitude: 12 hours and 8 minutes (New Orleans, Louisiana; Cairo, Egypt; and Shanghai, China)

• At or near 60 degrees north latitude: about 12 hours and 16 minutes (Helsinki, Finland and Anchorage, Alaska)

For truly equal day/night division, you have to wait until days or even weeks after the official equinox. This day is called the equilux, and when it occurs depends on your latitude.

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First day of autumn: why the equinox is not as equal as you might think