Twice a year, the sun shines equally on everyone, or so it seems. On September 22, 2024, we将迎来 our second and final equinox of the year. In the Northern Hemisphere, it marks the beginning of fall, while those south of the equator prepare for spring. However, the equinox isn't as perfectly balanced as you might think.

The Fall Equinox: A Global Phenomenon

The equinox arrives at 12:44 UTC, with local times varying across the globe. From Montreal to Mexico City, and from Amsterdam to Dubai, people will mark the occasion at different moments. Fall officially begins on the autumn equinox, but there's a subtle distinction between "astronomical seasons" and "meteorological seasons." Astronomical fall spans from the autumnal equinox to the winter solstice, while meteorological fall is a fixed period from September 1 to November 30.

The Tilt and the Twist of Seasons

The Earth's axis, tilted at 23.5 degrees, causes one hemisphere to receive more sunlight than the other, leading to seasonal changes. The summer solstice in June and the winter solstice in December have the most extreme day and night differences, especially near the poles.

Ancient Monuments and the Equinox

Our ancient ancestors were well aware of the sun's movement across the sky, building monuments like Stonehenge and the Megalithic Temples of Malta to mark the seasons. At Chichén Itzá, the pyramid casts a snake-like shadow on the equinoxes, a spectacle created by the Toltec-Maya people.

Cultural Celebrations of the Fall Equinox

The fall equinox is woven into various cultures and celebrations. In Greek mythology, it signifies the return of Persephone to the underworld. In China and Vietnam, the Harvest Moon Festival is celebrated with lanterns and mooncakes. In Japan, Autumnal Equinox Day is a national holiday with roots in Shintoism and Buddhism.

The Day Is Longer Than You Think

Despite the equinox's reputation for equal day and night, you actually get slightly more daylight due to the way sunrise is measured and the refraction of sunlight in our atmosphere. This effect causes the sun to appear above the horizon when it's actually below it, leading to longer days at higher latitudes.

The Equilux: A Day of True Balance

For a truly equal day and night, you'll have to wait a few days after the equinox for the equilux, a date that varies depending on your latitude. Closer to the equator, the equilux arrives later, and at the equator, it never arrives due to atmospheric refraction.