There is a question about the 24 solar terms, which I have never been clear about.

Twenty-four solar terms originated in the Yellow River Basin. As early as the Spring and Autumn Period, four solar terms were set, namely, mid-spring, mid-summer, mid-autumn and mid-winter. After continuous improvement and perfection, by the Qin and Han Dynasties, the 24 solar terms had been completely established. 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 ancients lived and produced for a long time, especially agricultural production. Through experience accumulation, observation, recording and some research, 24 solar terms have been formed, which embodies the labor wisdom of the ancient working people in China. The spring rain shakes the spring and clears the valley, and the summer is full of mountains and summers. Autumn dew, autumn frost, little snow in winter and cold in winter. The two festivals remain unchanged every month, with a maximum difference of one or two days. The first half of the year is June 2 1 day, and the second half is August 23.