This year the Autumnal or Fall Equinox arrives on September 22nd and marks the beginning of the Fall season.
An Equinox is an astronomical event that happens twice, once in spring and once in autumn, each year when the tilt of the Earth’s axis is inclined neither away from nor towards the Sun. During Equinoxes the tilt of the Earth (with respect to the Sun) is 0° and because of it duration of the day and the night are almost equal on Equinox day i.e. 12 hours.
Go to the link below and discover some fun facts about the first day of Fall.