What was the calendar like in the Eastern Han Dynasty? What are the related books?

Calendar is a long-term timing system. Specifically, it is the arrangement of year, month, day and time. Because farming activities are closely related to the changes of the four seasons, the calendar was originally produced by the needs of agricultural production. China has a long history of agricultural production, and there were many calendars in ancient times, among which taichu calendar in the Western Han Dynasty was the first relatively complete calendar.

In the early years of the Western Han Dynasty, the Zhuan Xu calendar of the Qin Dynasty was followed. However, there are some mistakes in Zhuan Xu Calendar. BC 104 (the sixth year of Yuanfeng), at the suggestion of Sima Qian and others, Emperor Wu of the Han Dynasty ordered the calendar to be changed. In BC 104, astronomers such as Luo He made a calendar. Taichu calendar stipulates that a year is equal to 365.2502 days and January is equal to 29.5086 days. Change October as the beginning of the year to the first month of the year; Beginning to adopt twenty-four solar terms that are beneficial to agricultural time; Dividing a month without neutral gas into leap months regulates the contradiction between the sun and the lunar calendar. This is an epoch-making progress in the history of China. Taichu calendar method also drew a solar eclipse cycle of 135 months based on astronomical observations and years of records by historians. Taichu calendar is not only the first relatively complete calendar in China, but also the most advanced calendar in the world at that time. It has been running for 189 years since it came out.

Taichu calendar [1] is the first calendar with complete written records in China. Although the data of the first month and the return year of the lunar calendar are not as accurate as the seasonal calendar, there are the following remarkable progress: the first month is the beginning of a year, and the month without neutral atmosphere is a leap month, which makes the months and seasons more reasonable; The rendezvous period of planets is measured accurately. For example, Mercury is 1 15.87 days, which is only 0.0 1 day less than today's measured value. The solar eclipse cycle of 135 months is adopted, in which the sun passes through the intersection of yellow and white for 23 times, and two times are an eclipse year, that is, 1 eclipse year =346.66 days, which is less than 0.04 days larger than the measured value today. Taichu calendar also included 24 solar terms in the calendar for the first time, which played an important guiding role in agricultural production.

The compilation of taichu calendar is the first major reform in the legal history of China. It is a calendar implemented from the first year of Emperor Wu of the Han Dynasty (BC 104) to the second year of the Eastern Han Dynasty (AD 85). According to astronomical observation and astronomical records over the years, the year of return is 365.438+06, and the first month of the lunar calendar is 29.5086. There are more than 20 people who revised the calendar in Emperor Wu of the Han Dynasty, including Sima Qian, Zhu Xi, and folk calendar calculators, Luo and so on. Taichu calendar's original work has been lost.