Summer 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.
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 Decatur and Avondale Estates, with sunset at 7:33 p.m.
Throughout history, groups have celebrated the autumn equinox, partly because it represents harvest time.
In Decatur, the equinox will be celebrated with a "group sound exploration" at 1:30 p.m. Sunday, Sept. 23, at Decatur Healing Arts at East Decatur Station at 619 E. College Ave., Suite B. Entry is $15.