On Sept. 23 at 2:50 a.m. EDT, the autumnal equinox ushered in a new season and fall officially began, per The Old Farmer’s Almanac.

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1. What exactly is an equinox?

An equinox, as defined by the National Weather Service, is all about the position of the sun in relation to Earth. As the Northern Hemisphere changes from summer to fall, the center of the sun and the centerline of the Earth match, and both hemispheres have the same amount of exposure to the sun.

As the sun passes that midline, the northern part of the Earth sees less of the sun, which causes shorter days and cooler temperatures, while the Southern Hemisphere enters spring with warmer weather and longer days.

2. Does fall always start on Sept. 23?

Fall includes the last part of September and lasts until Dec. 21, when the winter solstice begins.

Most of the time, the fall equinox occurs on Sept. 22 or 23, but very rarely can occur on Sept. 21 or 24.

3. How did ancient cultures observe the autumnal equinox?

Light was and is still a big player in many symbolic interpretations of the equinox and the shift to fall.

In ancient Greece, according to History, the autumnal equinox was celebrated at the time the goddess Persephone returned to the underworld to be with Hades. This was one explanation for why the days are shorter, leaving the world a little darker.

The Mayan people of Central America built monuments like Kukulcan, which showed a shadow of a snake on only two days each year, per National Geographic. Today, the Mayan people still celebrate the occasion by conducting a ceremony.

4. What cultures celebrate the fall equinox?

For modern-day Buddhists in Japan, the amount of light is not an important part, but where the light is matters. The west is considered the land of the dead, and since the sun sets in the west during this time, ancestors are celebrated and time is spent remembering them, per Higashi Honganji USA.

National Geographic’s photos show a diverse way of celebrating the fall equinox all over the world.

In Lithuania, National Geographic shows congregants still gathering at the shore of the Neris River and lighting candles to celebrate the new season.

Spain holds an annual parade through Soria during the autumn equinox where torches are lit in the streets and costumes are worn, which is shown in a photo by National Geographic.

Modern-day Stonehenge is a popular spot for neo-druids and Arthurian followers to celebrate the change of the season, as captured by National Geographic.

The harvest moon also occurs during this time of year, bringing even more traditions and celebrations to many different cultures.

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