What was the calendar like in the Three Kingdoms period?

Taichu calendar was mainly used in the Three Kingdoms period.

Derived knowledge points:

The first time to reform the calendar was the 8 1 minute calendar proposed by Luo et al. during the period of Emperor Wu of the Western Han Dynasty. As Emperor Wu of the Han Dynasty ordered the creation of a new calendar in the seventh year of Yuanfeng (BC 104), the seventh year of Yuanfeng was changed to the first year of Taichu, and the end of December was defined as the end of Taichu Yuan, that is, from the first month of Meng Chun to the end of December. This kind of calendar is called the original calendar. The length of this calendar is 29 43/8 1 day, so it is called eighty-one, or eighty-one calendar.

Taichu calendar is the first complete ancient calendar handed down from ancient times in China. Compared with the seasonal calendar, it has three improvements: taking the first month as the beginning of a year, distributing the 24 solar terms created by China in twelve months, and taking the month without neutral atmosphere as a leap month, which makes the months and seasons more reasonable; The measurement of the rendezvous period of planets is relatively accurate. For example, Mercury is 1 15.87 days, which is only 0.0 1 day less than the current measured value 1 15.88 days; The mating cycle of 135 months is adopted, that is, the annual feeding period is 346.66 days, which is only 0.04 days longer than the measured value today.

At the end of the Eastern Han Dynasty, Liu Hong (A.D. 158- 167) made a dry calendar, which reduced the mantissa of the tropical year to below 1/4 for the first time, to 365.2462 days. For the first time, he introduced the change of the speed of the moon movement into the calendar, becoming the first calendar with the algorithm of determining the new moon. This calendar also gives the value of the intersection of the ecliptic and the ecliptic about six degrees, and infers that an eclipse can only occur when the moon is within fifteen degrees from the intersection of the ecliptic and the ecliptic, which actually puts forward the concept of "food limit".