What are the four solar terms in autumn?

The fourth solar term in autumn is the autumnal equinox.

The autumnal equinox is the sixteenth of the twenty-four solar terms, and the time is generally from September 22 to September 24 of the Gregorian calendar every year.

The autumnal equinox means "equally divided" and "equally divided", which means equally dividing autumn except day and night. After the autumnal equinox, the position of direct sunlight moves south, and the days in the northern hemisphere become shorter, the nights become longer, the temperature difference between day and night increases, and the temperature drops day by day.