You might hear the term "autumn equinox" tossed around Sept. 22 on the first day of fall . But what exactly does that mean? Is it different from a solstice?

Yes, actually. They mark seasonal changes and the sun's relative position in the sky.

Here's what you should know about the autumnal equinox in 2025.

What is the autumn equinox?

There are two equinoxes and two solstices every year. Every 22nd or 23rd of September, the sun appears directly over the equator, marking the autumnal equinox .

Equinox means "equal night" in Latin, when nighttime and daytime are of nearly equal lengths across the planet.

On Sept. 22, 2025, summer officially changes into fall. The vernal equinox, by the way, is when winter changes into spring in the Northern Hemisphere.

In the Southern Hemisphere, it

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