Halloween, Thanksgiving & Autumn
The First Day of Fall - An equinox is an astronomical event in which the plane of Earth's equator passes the center of the Sun. Equinoxes occur twice a year, around 21 March and 23 September. In 2015, the autumnal equinox, the astronomical start of autumn occurs early Wednesday morning, September 23 at 4:21 a.m. ET, 3:21 a.m. CT, 2:21 a.m. MT, and 1:21 a.m. PT. The sun is directly above the equator, marking the autumnal equinox which may fall on any day of the 21st or 22nd or 23rd of September. The word equinox comes from the Latin words "aequalis" and "nox," meaning equal night.