Elaboration of taichu calendar law.

From May of the first year of Taichu to February of the second year of Emperor Hanyuan and Jiayin, *** 188 is the first existing ancient calendar in China. At the same time, it takes into account the laws of the apparent motion of the sun and the changes of the moon's profit and loss, and adopts the average value of the tropic year and the first month of the lunar calendar as the basic cycle, which belongs to the yin-yang calendar and inherits the scientific and rational nature of the ancient Chinese yin-yang calendar. The adoption of Xia Zheng-taking silver moon as the beginning of the year, keeping pace with the farming rhythm of spring planting, summer busy, autumn harvest and winter leisure, has brought great convenience to guide the production and life of agriculture and animal husbandry. Taichu calendar also takes the months with no neutral atmosphere (even numbers in the 24 solar terms, namely winter solstice, severe cold, fright, vernal equinox, Qingming, Xiaoman, summer solstice, general department, local department, autumn equinox, first frost and light snow) as leap months, which is more reasonable than the previous year-end leap method. Its mating cycle and five-star rendezvous cycle are more accurate. The equatorial distance (right ascension difference) measured by taichu calendar has been used for more than 800 years, and it was not until the thirteenth year of Tang Kaiyuan that it was replaced by a line of re-measuring the rhyme value.

With the development of agricultural production, it is obvious that this political year is out of touch with the common spring, summer, autumn and winter that people are used to. So Dr. Gong Sunqing, Dr. Hu Sui and Mr. Tai Shiling suggested that Sima Qian modify the calendar. At the same time, after the early Han Dynasty, people did make some progress in astronomical observation and knowledge, which created good conditions for revising calendars. In the seventh year of Yuanfeng, Liang Wudi (BC 104), the first day of November happened to be Jiazi Festival, and it also coincided with the solar term of winter solstice, which was a rare opportunity.

In May of this year, Emperor Wu of the Han Dynasty ordered Gong Sunqing, Hu Sui, Sima Qian and others to discuss and create the "Han Li", and collected more than 20 folk astronomers, including Sima Ke of Changle, the alchemist of Jiuquan County and Luoxiahong of Ba County. They either measure calendars with instruments or calculate them by extrapolation. They debated, compared and tested the proposed 65,438+08 calendar changes, and finally chose the 8 1 minute calendar proposed by Heluo. 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. Since then, every year starts from the first month in Meng Chun and ends at the end of December. This calendar is called taichu calendar, which was first promulgated in China according to certain regulations. From the process of changing the calendar, it can be seen that there were deep astronomical researchers in both the ruling and opposition parties at that time, which can be said to be rich in talents. In particular, a large number of astronomers come from the private sector, which shows that the study of astronomy has been widely concerned by the society and has a solid foundation. In ancient China, the principle that calendars must be determined by astronomical observation was confirmed and fully embodied, which had a far-reaching impact on the formulation of calendars in later generations. Its presentation is epoch-making.

Taichu calendar's basic constant is 29.45438+0 days in the first lunar month, so it is called eighty-one method, or eighty-one calendar. The number of days in this moon is more than that in the April calendar of the Warring States Period, which is of course not accurate enough, but the promulgation and implementation of taichu calendar has been tested. In the third year of Yuanfeng (78 BC), a surname ordered Zhang Shouwang to oppose the implementation of the taichu calendar and advocate the use of the lunar calendar. After the experiment, due to the alienation of lunar calendar, the calendar is still in use.

Taichu calendar's method has already included Qi Shuo, leap method, five stars, mating cycle and so on. For the first time, the principle of taking the month without neutral atmosphere (rain, vernal equinox, Grain Rain and other twelve solar terms) as leap month was put forward, and the relationship between seasons and months was very reasonably adjusted, which has been used until the lunar calendar (summer calendar).

Taichu calendar also clearly put forward the concept of 135 lunar month with 23 food seasons for the first time, and the accuracy of the five-star rendezvous was also improved obviously. Based on the dynamic understanding of the five stars during the rendezvous, a calendar for calculating the positions of the five stars is established. All these set an example for later calendars.

The original taichu calendar has long been lost. At the end of the Western Han Dynasty, Liu Xin basically adopted the data of taichu calendar, and changed it to three calendars according to taichu calendar. Was it collected in Hanshu? In the legal calendar, it has been passed down to this day. In fact, the calendar is named after the change of yuan, while the three calendars are named after the dharma number. Liu Xin systematically expounded Deng Ping's 81-point method, supplemented a lot of original and brief astronomical knowledge and textual research on astronomical documents since ancient times, and wrote three calendars. "Saint Litongpu" is based on unity and discipline. Unity is to calculate the distance between the sun and the moon (chán, a certain area where the sun and the moon run), and discipline is to calculate the visibility of five stars.

Unity and discipline are different. Mom talks about legislative principles, and technology talks about calculation methods. Thus, there were the names of Mu Tong, Jim, Shu Tong and Ji Shu; There is also dating technology, which is based on calculating the position of wood stars. There are five other steps, namely, measuring five stars to verify the correctness of legislation; In addition, there are world classics, that is, the ancient year of postgraduate entrance examination, to prove whether its method is based. This is seven parts of three calendars. This calendar is a complete astronomical work handed down from ancient China. Its contents include calendar making theory, solar term constant, eclipse constant, five-star constant, calculation and step-by-step method; There is also the distance between the basic stars, which can be said to contain the basic contents of modern astronomical almanac, so the "three calendars" are considered as the embryonic form of the earliest astronomical almanac in the world.

The conditions mentioned in the three calendars for calculating the theory of qi according to the root sum principle are all complete. Forget it. Say it.

On the one hand, its starting point is to stipulate that the number of days in January is 29.4438+0; The rest of the days, on the contrary, come from this new moon or accommodation.

The number of days, months and return years in the first lunar month are too large.

Chapter 1 = 19 =235 In this cycle, the winter and sunset in Shuodan are on the same day.

1 series =8 1 chapter =1539 = 562120th = 19035 In this cycle, the winter solstice in Shuodan coincides with the midnight of that day.

1 yuan =3 series =46 17 In this cycle, the winter solstice in Shuodan resumes at midnight on the day of Jiazi. Because the unified number of days is 562 120 divided by 60, and there is still 40. Therefore, if Jiazi's date is taken as a yuan, you will get Chen Jia after reunification, Shen Jia after two reunions and Jiazi after three reunions. This is the origin of the name "San Tong". This meta-method 46 17 cannot be divisible by 60, so the year number of the head of state cannot be the same.

The beginning of the three-series calendar was in Jiazi in the middle of winter seven years ago in Han Yuanfeng. According to the records of the laws and calendars of the Han Dynasty, it was actually observed at that time, and it won the winter solstice, so it was renamed the first year of Taichu.

In addition to the midnight solstice of Jiazi, the ancients also cooperated with the cycles of the sun, the moon and the five stars, so the three-series calendar set a large cycle of 5 120 yuan, that is, 3639040 years, which was originally called Tai Chi Shangyuan, and the cumulative year from the second year of Tai Chi Shangyuan was set to14365,438+027 years, that is, 3/3.

San Li is the first calendar in China that uses intersecting years and stars and months. The method of setting leap is to determine the leap surplus first, that is, several 19 o'clock in the winter solstice (the number of days in January) a year ago. The order of the names of twenty-four Qi is the same as that contained in Huainanzi Astronomical Training. It is also said that odd-numbered gases, such as cold and rain, are neutral gases from winter to the sun; Occasionally, qi, such as slight cold and beginning of spring, is a solar term. However, in Sanlitong Spectrum, the order of rainwater and Jingzhe is reversed, while the order of Qingming and Grain Rain is reversed, and the order of other gases has not changed. The order of these four solar terms changed because of Liu Xin's own prejudice, not the calendar that people followed at that time.

Taichu calendar is based on astronomical observation records and combined with production practice, and its content is much richer than the previous Zhuan Xu Calendar. The astronomical data and calculation method of the calendar recorded in "Sheng Li Tong Pu" are scientific, which has become a model for later calendars. At the same time, most of the scholars in the Western Han Dynasty used Confucian classics to guide various systems. In order to support the reform of Wang Mang's ancient trust system, Liu Xin also used the Book of Changes to explain the astronomical data of taichu calendar, which has a distinct color of Confucian classics.

When Wang Mang usurped the Han Dynasty, December in summer was the first month, which was the beginning of the year. Calendar constants still use the values of these three calendars. Three calendars were also used in the early Eastern Han Dynasty, and the taichu calendar method began in the first year of Taichu (BC 104).

Used in the first year of Yuanhe in the Eastern Han Dynasty (AD 84), 188.