How did the ancients judge the 24 solar terms? An introduction to the ancient methods of judging the 24 solar terms.

1, there are two main ways for the ancients to calculate and determine the 24 solar terms:

(1) dichotomy, which divides a year into 24 equal parts on average, that is, 365.2422 days /24 = 15.2 18 days, that is, the average interval between two solar terms is 15 days;

(2) The method of "fixing qi" is unreasonable because the sun moves unevenly on the ecliptic every day, moving faster in winter and slower in summer. In this way, the ancients created the method of fixing qi to specify the specific date of solar terms, so that the vernal equinox and autumnal equinox must be equally divided day and night, and the position of the sun on the ecliptic of the year is divided into 24 segments, distributed in December and every month of the lunar calendar. There are twelve solar terms such as beginning of spring, Jingzhe, Qingming, Changxia, Mangzhong, Xiaoshu, beginning of autumn, Bailu, Hanlu, beginning of winter, Heavy Snow and Slight Cold. Mid-month is called "Zhongqi", which includes rain, vernal equinox, Grain Rain, Xiaoman, summer solstice, big trees, early trees, autumn equinox, early frost, light snow and winter solstice.

2. The systematic record of the twenty-four solar terms began with Zhoupian and Huainanzi. It accurately reflects the relationship between the sun and the earth formed by the revolution of the earth, which is very consistent with the cold, warm, dry and wet climate changes in the Yellow River basin in a year, and it is more convenient to grasp the agricultural time according to the full moon and short month. It is a great creation of indicating time mode in China's agriculture, and it still plays a guiding role in agricultural production.