There are 24 solar terms in vassal countries. Why does Qi have 30 solar terms?

China's astronomical calendar has a long history. As early as the Shang and Zhou Dynasties, the 24 solar terms were basically determined, and the four seasons of the year were divided into twelve months. However, it happened that one country engaged in "different politics" and implemented 30 solar terms, but it was not groundless. Adapting measures to local conditions may be the reason for this feature.

Qi also admitted that there are four seasons in a year, namely "spring, summer, autumn and winter". However, according to future generations' speculation, the State of Qi may not implement the December system, but the October system, that is, every month is 36 days, and every 12 day is a solar term, and there are only 360 days in a year, so there will be 30 solar terms.

There are two main arguments about why Qi set 30 solar terms. One is the theory of climate and environment. This view holds that Qi is close to the ocean and belongs to warm temperate humid monsoon climate, which is very different from the typical temperate monsoon climate in Shaanxi at that time in agricultural production, mainly characterized by short spring and autumn, long winter and summer. Therefore, the ruler of Qi noticed this and found that if it could be divided more carefully, it might be helpful to agricultural production, so the thirty solar terms came from it.

The second theory is "Yin-Yang and Five Elements Theory". The ancients really attached great importance to the theory of Yin and Yang, and attached importance to the art of mutual restraint. In Guanzi, a year is divided into five equal parts, all of which belong to Jin Mu's five elements of fire, water and earth, which are repeated to form an organism and 30 solar terms. It is said that the theory of five elements in the Central Plains also originated from Zou Yan in Qi State, which was greatly influenced by the solar terms in Qi State.

Of course, individuals are more optimistic about the "climate theory." After all, solar terms are more for agricultural production, and the five elements theory is just a gimmick. Of course, the twenty-four solar terms have passed, so it is ok for everyone to know.