The Big Dipper indicates December
In the Huainan zi astronomical training, it is said: "Emperor Zhang Siwei, luck to fight, the moon migrates to a chen, return to its place, the first month refers to Yin, December refers to ugly, one year old turns, and finally begins again." The "bucket" here refers to the handle of the Big Dipper.
In ancient times, the operation of the Big Dipper was used to calculate the moon order, and the tatsu pointed to by the bucket handle was called "Dou Jian". It is also the "monthly construction" in the calendar.
The Book of Han and the Vinaya Chronicle: "The solstice is the beginning of the festival, and the dou jian is the twelfth day, and the second is known according to its construction." ”
It is clearly stated in the Book of Han and the Chronicle of the Laws: "The One who is chen, the meeting of the sun and the moon, and the establishment of the reference." "It explains tatsu, what Yue Jian refers to.
The "(month) jian refers to" mentioned here, that is, the Beidou refers to, called Doujian, for example, the "History and Almanac" collection of interpretations says: "With the Douyu refers to the construction of December" .
The Five Elements of Righteousness. The Seven Politics quotes Shang Shuwei as saying: "The Big Dipper dwells in the heavens, and when Kunlun is above, the operation refers to it, with the twenty-four qi, the twelve chen, and the twelve months of construction,...... The state and the country are divided into years and years, and they are not in charge. ”
The so-called "moon construction" is to divide the twelve equal parts of the week near the ecliptic (that is, the route of the sun moving once a year in the sky), from east to west with the twelve branches of the child, ugly, yin, 卯, 辰, 巳, noon, wei, shen, 酉, 戌, and 海.
So how does the Big Dipper handle indicate twelve months?
In the Book of Rites, "The Moon of Meng Chun," Zheng Noted: "Meng, Changye." The journey of the sun and the moon, one year old and twelve, the holy king was divided because of his meeting, thinking that it was a big number. Guan Dou was built, and his life was four hours. This cloud Mengchun, the sun and the moon will be in the succubation, and the Dou Jianyin's Tatsuya is also. "Dou, the Beidou, follows the heavens and turns, and builds on the first day of January, thirty degrees ninety-six quarters of forty-two." First month Jianyin, February Jianjian, March Jianchen, April Jianwei, May Jianwu, June Jianwei, July Jianshen, August Jianyou, September Jianjiao, October Jianhai, November Jianzi, December Jianuya"
At the beginning of the dusk, the Seven Stars of the Big Dipper appear, the bucket handle refers to the first month, the bucket handle refers to February, the bucket handle refers to March, the bucket handle refers to April, the bucket handle refers to the afternoon as May, the bucket handle refers to June, and the bucket handle refers to July. Bucket handle refers to Unitary for August, Bucket Handle refers to September, Bucket Handle refers to October, and Bucket Handle refers to November. Bucket handle refers to the ugly for December.
Figure Big Dipper Seven Stars "Monthly Calendar"
In terms of one day, every day from the perspective of the earth where it is located, the Seven Stars of the Big Dipper orbit the North Star from east to west with time, moving a branch of the earth (also 30 degrees on a sunday) every hour (that is, two hours), and the twelve branches of the day are exactly one week, which coincides with the "Sunday visual movement" of the sun. Due to the difference between Dou Jian (the moon order), the position of the Seven Stars of the Big Dipper on the celestial sphere is also different at different moon orders, although they are at the same hour.
Since the midnight "sub-time" is not only the end of the change of yin and yang of day and night, but also the beginning of the change of yin and yang of a new day, at the same time, the winter solstice "sub-moon" is exactly when the handle of the Big Dipper points to the north, so it is very important.
The twelve branches are spaced 30 degrees apart, and there is an equal solar return year, and each branch corresponds to the twelve months of the year, that is, the so-called "twelve months of the year, the day has twelve days" ("Lingshu Wei Qi Xing").
