Summer is almost over. It officially ends at 10:49 a.m. Saturday. That's the moment when the Autumnal Equinox occurs in the Eastern United States, according to the Old Farmer's Almanac.

The Alamanac explains what's happening:

On the first day of fall—the autumnal equinox—day and night are each about 12 hours long (with the actual time of equal day and night, in the Northern Hemisphere, occurring a few days after the autumnal equinox). The Sun crosses the celestial equator going southward; it rises exactly due east and sets exactly due west.

Days and nights also have equal length in the spring equinox, too. On Saturday, sunrise occurs at 7:25 a.m. in Atlanta, with sunset at 7:33 p.m.

Throughout history, groups have celebrated the autumn equinox, partly because it represents harvest time.

Nearby, Kashi Atlanta is celebrating the occasion with Fall Equinox Yoga & Mediation on Sept. 23 from 1:30-4 p.m. Cost is $30.

Do you know of other events to mark the start of fall? Add them in the comments area below!