When were the 24 solar terms formed?

As early as the Eastern Zhou Dynasty, the Spring and Autumn Period and the Warring States Period, the working people of the Han nationality had the concept of "being far away from the north" and "being far away from the north". Subsequently, people divided the year into 24 equal parts according to the natural phenomena such as the running position of the sun and the moon at the beginning and middle of the month, the weather and the growth of animals and plants. And gave each division a proper noun, that is, twenty-four solar terms. By the end of the Warring States Period, solar terms had eight names: beginning of spring, Equinox, Long Summer, Summer Solstice, beginning of autumn, Equinox, beginning of winter and Winter Solstice. These eight solar terms are the most important of the 24 solar terms. Mark the seasonal changes and clearly divide the four seasons of the year.

By the Qin and Han Dynasties, the 24 solar terms had been completely established.

The book Huai Nan Zi has exactly the same name as the modern twenty-four solar terms. In BC 104, the taichu calendar written by Deng Ping officially set 24 solar terms in the calendar, and defined the astronomical position of the 24 solar terms.

The names of the 24 solar terms are named according to the place pointed by Dougang and the natural climate and landscape at that time. The so-called fighting means that the three stars of the Big Dipper, Kuixing, Xingxing and Yuxing, point to different directions and positions with the movement of celestial bodies, and the positions they refer to are the months they represent. For example, the first month is cloudy, dusk refers to cloudy, midnight refers to cloudy, and daytime refers to cloudy. February is the base, at dusk, at midnight, during the day, and so on.