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lite.cnn.com - on gopher - inofficial | |
ARTICLE VIEW: | |
Fall equinox: Why the first day of fall isn’t as equal as you might | |
think | |
By Forrest Brown, CNN | |
Updated: | |
7:15 AM EDT, Thu September 18, 2025 | |
Source: CNN | |
Twice a year, the sun doesn’t play favorites. Everyone on Earth is | |
seemingly on equal status – at least when it comes to the amount of | |
light and dark that they get. | |
On Monday, we enter our second and final equinox of 2025. If you reside | |
in the Northern Hemisphere, you know it as the . For people south of | |
the equator, this equinox actually heralds the coming of . | |
Technically, your location on the globe also determines the local time | |
and even the date you experience the fall equinox. For the Americas, | |
Africa and Europe, it’ll take place on Monday, September 22. For some | |
destinations in Asia, it’ll be the next day. | |
People close to the equator won’t notice anything — they have | |
roughly 12-hour days and 12-hour nights all year long. But hardy folks | |
close to the poles, in places such as Alaska and the northern parts of | |
and Scandinavia, go through wild swings in the day/night ratio each | |
year. They have long, dark and then have a where night barely intrudes. | |
But during the equinox, everyone from pole to pole gets to enjoy a | |
12/12 split of day and night. Well, there’s just one rub — it | |
isn’t as perfectly “equal” as you might have thought. | |
There’s a good explanation for why you don’t get precisely 12 | |
hours of daylight on the equinox. More on that farther down. | |
Here are the answers to some fall equinox questions: | |
Where does the word ‘equinox’ come from? | |
From the : The term equinox comes from the Latin word equinoxium, | |
meaning “equality between day and night.” | |
Precisely when will the fall equinox happen? | |
The at 18:19 UTC (Coordinated Universal Time) Sunday, September 22. | |
For people in places such as Montreal and , that’s 2:19 p.m. local | |
time. It comes at 1.19 p.m. in St. Louis and 12.19 p.m. for Mexico | |
City. Even further westward, that’s 11.19 a.m. for Seattle. | |
Going in the other direction across the Atlantic Ocean, residents of | |
Amsterdam and Split, Croatia, will officially mark the occasion at 8.19 | |
p.m. Sunday. Traveling even farther east, Dubai marks the exact event | |
at 10.19 p.m. | |
For residents of Hong Kong, it’s 2:19 a.m. on Monday, September 23. | |
In Tokyo, it’s 3:19 a.m. on the same day. You can . | |
Is autumn equinox the official first day of fall? | |
Yes. Fall officially begins on the autumn equinox. | |
But there are actually two measures of the seasons: “the astronomical | |
seasons” (which follow the arrivals of equinoxes and solstices) and | |
what’s called the | |
Allison Chinchar, CNN meteorologist, explains the differences: | |
“Astronomical fall is essentially the time period from the autumnal | |
equinox up to the winter solstice. Those dates can vary by a day or two | |
each year,” she says. | |
“Meteorological fall is different … in that the dates never change | |
and are based on climatological seasons rather than Earth’s angle | |
relative to the sun. These are perhaps the seasons that more people are | |
familiar with,” Chinchar says. | |
Meteorological seasons are defined as the following: March 1 to May 31 | |
is spring; June 1 to August 31 is summer; September 1 to November 30 is | |
autumn; and December 1 to February 28 is winter. | |
“This makes some dates tricky,” Chinchar says. “For example, | |
December 10, most people would consider winter, but if you are using | |
the astronomical calendar, technically that is still considered autumn | |
because it is before 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 falls in line | |
more with what people think traditional seasons are.” | |
Why does fall equinox happen? | |
The Earth rotates along an imaginary line that runs from North Pole to | |
South Pole. It’s called the axis, and this rotation is what gives us | |
day and night. | |
However, the axis tilts at 23.5 degrees, . That positions one | |
hemisphere of the planet to get more sunlight than the other for half | |
of the year’s orbit around the sun. This discrepancy in sunlight is | |
what triggers the seasons. | |
The effect is at its maximum in late June and late 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 each day during the summer in places such as Scandinavia.) | |
Since the summer solstice in June, days have been progressively | |
becoming shorter in the Northern Hemisphere and the nights longer for | |
the past three months. Welcome to fall equinox! | |
What did our ancestors know? | |
Long before the age of clocks, satellites and modern technology, our � | |
about the movement of the sun 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 sites associated with the equinox and the | |
annual passage of the sun: | |
: Many remain, but we do know they are aligned to mark the yearly | |
passage of the sun. | |
: These seven temples on the Mediterranean island are some of the | |
earliest free-standing stone buildings in the world, going back 5,000 | |
to 6,000 years ago. At temples, the semicircular chambers are | |
aligned so that the rising sun on an equinox is framed between the | |
stones. | |
•: El Castillo, the famous pyramid at Chichén Itzá, puts on a | |
striking show on the equinoxes. Constructed by the Toltec-Maya people� | |
, the pyramid was built to cast a shadow during equinoxes on the | |
northern balustrade of El Castillo. It looks like the form of a snake | |
slithering down the stairs, and the ancient special effect is | |
heightened by the heads of sculpted beasts at the base. | |
•: Much more recent in origin (1724 and 1730), these buildings from | |
the end of the Mughal period are astronomical observatories. | |
What are some fall equinox festivals and rituals? | |
All around the world, the fall equinox has weaved its way into our | |
cultures and celebrations. | |
In Greek mythology, the fall equinox marks the return of the to the | |
underworld for three months, where she is reunited with her husband, | |
Hades. | |
Harvest festivals had their roots in fall equinox since pagan times. | |
still celebrate the Harvest Moon (also known as the Mid-Autumn | |
Festival). Lanterns line the streets as people give thanks, watch the | |
moon and eat. Round pastries called are a Mid-Autumn Festival favorite. | |
It’s held on the 15th day of the eighth lunar month on the Chinese | |
calendar. That was held on September 17 this year. | |
In Japan, . In Japanese, it’s known as Shubun no Hi (秋分の日),� | |
. The roots of the celebration are thought to go back to Shintoism and | |
Buddhism. | |
So why isn’t the equinox exactly equal? | |
It turns out you get a little more daylight than darkness on the | |
equinox, depending on where you are on the planet. How does that | |
happen? The answer is complicated but fascinating. | |
The “nearly” equal hours of day and night are because of a sunrise | |
is measured and the refraction of sunlight in our atmosphere. | |
This bending 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 a | |
bit longer at higher latitudes than at the equator because it takes the | |
sun longer to rise and set the closer you get to the poles. | |
So on fall equinox, the length of day will vary a little depending on | |
where you are. Here are a few breakdowns to give you an approximate | |
idea: | |
• At the equator: About 12 hours and 6 minutes (Quito, Ecuador) | |
• At 30 degrees latitude: About 12 hours and 8 minutes (Cairo, Egypt) | |
• At 60 degrees latitude: About 12 hours and 14 minutes (Helsinki, | |
Finland) | |
For the truly equal day/night split, you have to wait some days after | |
the official equinox. That’s . When the equilux happens for you | |
depends on your latitude, according to . The closer you are to the | |
equator, the later the date for the fall equilux. | |
And at the equator itself, the equilux never arrives because of that | |
aforementioned atmospheric refraction of the sunlight. There’s always | |
a little more daylight than darkness along that line. | |
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