During an equinox, places around the globe experience nearly equal amounts of daytime and nighttime. The second occurrence this year happens on Sunday.

According to Britannica, the Autumnal Equinox is one of two moments in the year when the Sun is exactly above the Equator. The celestial event happens every year around Sept. 22 or 23 in the Northern Hemisphere, but fall officially starts on March 19 or 20 in the Southern Hemisphere.

Today is the first day of Autumn but why is the first day of Fall different each year? As of 7:43, this morning marks the start of the first day of Fall (astronomically speaking)! The Autumnal Equinox marks the change in seasons from summer,

The autumnal equinox is considered the first day of fall, but it’s so much more than that. The word equinox comes from two Latin words: “aequus,” meaning equal, and “nox,” meaning night, the National Weather Service explains on its website.