The autumnal equinox

The autumnal equinox is the sixteenth of the twenty-four solar terms and the fourth in autumn. Douzhiyou; the sun reaches 180° ecliptic longitude; it meets on September 22-24 of the Gregorian calendar every year. On the autumnal equinox, the sun almost directly hits the earth's equator, and day and night are equal in length around the world . On the autumnal equinox, "fen" means "equal division" and "half". In addition to referring to the equal division of day and night, there is also a layer of meaning equal to the division of autumn. After the autumnal equinox, the position of direct sunlight moves southward, the days in the northern hemisphere are shorter and the nights are longer, the temperature difference between day and night increases, and the temperature drops day by day.

The autumnal equinox used to be the traditional "Sacrificing Moon Festival", and the Mid-Autumn Festival evolved from "Sacrificing the Moon on the Autumn Evening" . On June 21, 2018, the State Council of the People's Republic of China issued the approval for the establishment of the "Chinese Farmers Harvest Festival", agreeing to establish the annual autumn equinox as the "Chinese Farmers Harvest Festival" starting from 2018.