Saturday, Sept. 23, marks the first day of fall 2023 in the Northern Hemisphere.

Saturday’s autumnal equinox marks the beginning of astronomical fall and the end of summer north of the equator.

In the Southern Hemisphere, Saturday marks the first day of spring and the end of winter.

The moment of the 2023 fall equinox will come at 1:50 a.m. CDT Saturday (Sept. 23). That marks the instant that the Sun shines directly over the equator, giving nearly equal amounts of day and night throughout the world (except for the North and South Poles), according to NASA.

After Saturday’s equinox, the Sun will continue to rise later and set earlier in the Northern Hemisphere, while the days will grow longer in the Southern Hemisphere.

The equinox is the most popular marker of fall, but there’s also meteorological fall, which began on Sept. 1.

Meteorological seasons are marked in three-month blocks that are dictated by the temperature cycle. Astronomical seasons are marked by twice-yearly solstices (summer and winter) and the equinoxes (fall and spring).

The next big marker of the season will be the change over to Standard Time, which will be on Sunday, Nov. 5.

Also upcoming will be the harvest moon, which will at its fullest on Sept. 29. It will also be the last of four super moons in 2023.

Meteorological winter begins on Dec. 1, and the winter solstice will be on Dec. 21.