How were the 24 solar terms in China determined in ancient times?

In ancient China, a year was divided into 24 solar terms, which was not based on the lunar calendar. The earth goes around the sun once, which is a year in the solar calendar. The ancient Chinese did not have the concept of "solar calendar", but he regularly observed the sun or other stars and galaxies from the earth (for example, at noon every day). He assumes that the earth is motionless, so the position of the sun is different from that of the earth at noon every day. Then, he wrote down the points of the sun's movement in the sky (stars) observed in a year until it coincided with the first point and formed a "circle". This "circle" was called "ecliptic" by the ancients. (The auspicious day of the ecliptic is inferred from this)

Divide the ecliptic into 24 equal parts, each equal part is 15 degrees, and each equal part is just a sun point.

In ancient China, the 24 solar terms were divided by dividing the ecliptic equally. A period of the ecliptic coincides with a year in the solar calendar.