The origin of the autumnal equinox solar terms, what is the story of the autumnal equinox solar terms?

According to China's ancient book Spring and Autumn Stories? The first chapter "Yin and Yang in and out" said: "The autumn equinox, Yin and Yang are also half-phase, so it is cold and hot day and night. "The autumnal equinox means' half'. Therefore, the autumnal equinox has two meanings:

1. On this day, the sun reaches 180 degrees of the ecliptic and directly hits the equator of the earth, so this day is divided into 24 hours, each 12 hours. There is no extreme day and night phenomenon in the world. Like the vernal equinox, in a day, day and night are equally divided.

2. According to the seasonal division method in ancient China, which took beginning of spring, Changxia, beginning of autumn and beginning of winter as four seasons, the autumnal equinox lived in autumn for 90 days and divided the autumn equally. So it is called "autumnal equinox".