How did China set the calendar in ancient times?

The evolution of ancient calendars in China can be roughly divided into five periods.

1. Ancient calendar period: the calendar adopted by Emperor Wu of the Han Dynasty before the first year of Taichu;

2. Sino-French period: from the first year of Han Dynasty to the early Qing Dynasty. During this period, more than 70 people made calendars, all of which were written into the twenty-four histories or laws and regulations.

3. Chinese and Western legal periods: from Tang Ruowang, a Soviet missionary in Qing Dynasty to the Revolution of 1911;

4. Gregorian calendar period: After the Revolution of 1911, Dr. Sun Yat-sen announced the adoption of the Gregorian calendar in 19 12.

5. Combination of lunar calendar and lunar calendar: After the establishment of People's Republic of China (PRC), the Gregorian calendar was adopted and the traditional lunar calendar of China was promulgated, taking into account the actual needs of people's production and life.

Calendar, simply put, is to measure a long time interval, judge the climate change and predict the coming season according to the natural law of astronomical changes. The history of ancient astronomy in China, in a sense, is a history of calendar reform. Throughout the ancient calendar of China, it contains a lot of contents, including the calculation of new moon, 24 solar terms, leap moon, solar eclipse and the calculation of planetary positions.