What does the autumnal equinox mean?

The autumnal equinox is the sixteenth solar term among the twenty-four solar terms and the fourth solar term in autumn.

Fight refers to unitary; The sun reaches the yellow meridian180; Celebrated on September 22-24 of the Gregorian calendar every year. On the day of the autumnal equinox, the sun shines almost directly on the equator of the earth, and the length of day and night is equal all over the world. 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.

The autumnal equinox used to be the traditional "Moon Festival", and the Mid-Autumn Festival evolved from the "Autumn Moon Festival". On June 2, 2065438, People's Republic of China (PRC) * * and the State Council issued an official reply on agreeing to set up the "China Farmers Harvest Festival", agreeing to set up the annual autumn equinox as the "China Farmers Harvest Festival" from June 20, 2065438.

Astronomical calendar:

On the day of the autumnal equinox, the point of direct sunlight reaches longitude 180 (autumnal equinox), almost directly to the equator of the earth, and the length of day and night is the same all over the world (regardless of the refraction of sunlight by the atmosphere and the dim shadow in the morning). After the autumnal equinox, the direct point of the sun continued to move from the equator to the southern hemisphere, and the days in the northern hemisphere began to shorten and the nights became longer, that is, the days in a day began to be shorter than the nights; The southern hemisphere is the opposite. Therefore, the autumnal equinox is also called the landing point. At the North Pole and South Pole, on the day of the autumn equinox, the sun is on the horizon all day.

In the same solar term, every year is 6 hours or 5 hours later than the previous year, and the leap year is 24 hours earlier. In this way, the date reflects that the same solar term remains unchanged or lags behind the previous year 1 day; The leap year remains unchanged or is earlier than the previous year 1 day. In this way, the starting point of the same solar term has three different Gregorian calendar dates. Take the "autumnal equinox" as an example, there are three situations: September 22nd, September 23rd and September 24th.

The above contents refer to Baidu Encyclopedia-Autumn Equinox.