When is the autumnal equinox

Autumnal equinox time of 2023: September 23rd 14: 49: 46.

The autumnal equinox is one of the 24 solar terms of the China lunar calendar, which usually appears on September 22nd or 23rd of the Gregorian calendar. At the autumnal equinox, the sun shines directly at the equator of the earth, with equal time between day and night, and the direct point of the sun gradually moves south from the tropic of cancer.

The autumnal equinox marks the turning point of the season, which means that autumn is officially coming. At this time, the time between day and night is basically equal, which means that the days are getting shorter and shorter and the nights are getting longer and longer. The temperature began to drop gradually, the leaves of plants turned yellow and red, and autumn scenery became colorful.

People have some traditional customs and activities in the autumn equinox. One of the customs is to eat autumnal equinox cake, which is a kind of cake made of bean paste, sesame seeds and walnuts, symbolizing reunion and bumper harvest. In addition, there will be some sacrificial activities, such as ancestor worship and grave sweeping.

Autumnal equinox 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.