The official first day of fall, otherwise known as the autumnal equinox, is this weekend in the Northern Hemisphere. According to Encyclopedia Britannica, it is one of only two days, the other being the vernal equinox, when the sun is directly above the Equator, essentially dividing night and day into equal portions.

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,

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.

The official start to the fall season, the autumnal equinox, occurs on Sunday, Sept. 22. What exactly happens during the equinox? Here’s a breakdown: According to NOAA, an equinox occurs when the Earth’s axis is tilted neither away nor toward the sun.

The autumnal equinox brings fall to the Northern Hemisphere today as the sun passes directly over the equator at noon. But are day and night actually equal length today?

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

If you get up early enough, you can experience an equinox sunrise. The autumnal equinox heralds the arrival of fall in the northern hemisphere.