Twenty-four solar terms left over from ancient times

As early as the Spring and Autumn Period and the Warring States Period, people already had the concepts of Solstice in the South and Solstice in the North. Then, according to the natural phenomena such as the running position of the sun and the moon at the beginning and the middle of the month, the weather, the growth of animals and plants, and using their relationship, people divide the year into 24 equal parts, and take their own names accordingly, forming 24 solar terms. During the Warring States Period, beginning of spring, vernal equinox, Changxia, Xia, beginning of autumn, vernal equinox, beginning of winter and winter solstice were listed in the "December" of Lv's Spring and Autumn Annals, which is also the most important of the 24 solar terms. These eight solar terms clearly divide the four seasons of the year. Later, in the Western Han Dynasty, the book Huainanzi had the same name as the modern twenty-four solar terms.

Because the lunar calendar in China is based on the movement of the sun and the moon, it is a kind of "yin and yang calendar", so it can't fully reflect the solar cycle. However, China is also a big agricultural country, and agriculture requires us to have a strict understanding of the operation of the sun, which is why the "twenty-four solar terms" which separately reflect the operation cycle of the sun came into being. The twenty-four solar terms accurately reflect the seasonal changes, so in China, the twenty-four solar terms are mainly used to guide agricultural activities, affecting the food, clothing, housing and transportation of thousands of farmers in Qian Qian.