Autumn will begin at 7:50 am tomorrow, Saturday, September 23rd, the time when the Sun will cross the plane of the Earth's equator again.
From this moment on, the Sun will be seen below the equator, hence, in the northern hemisphere, this event is designated as the autumnal equinox.
Despite this name, it is only three days later that the duration of the night will be the same as that of the day, because, due to atmospheric refraction, the Sun is always seen slightly above its real position, advancing each dawn and delaying each dusk.
Autumn 2023 will last until December 22nd, the day winter begins.
The seasons occur due to the Earth's tilt and its movement around the Sun, the translation, which lasts 1 year.
The beginning of the seasons is marked by the solstices and equinoxes. Each of them takes place twice a year. There are the Summer and Winter solstices and the Spring and Autumn equinoxes.