How is the lunar calendar compiled? Why is it cold in April this year? How did the ancients know?

The definition of sun, moon and year can not be separated from the system of Zhou Dynasty. Therefore, the Xia calendar was influenced by the system of Zhou Dynasty at that time. Let's introduce them one by one. (The calculation of time and moon phase here is based on east longitude 120 degrees (Purple Mountain Observatory in Nanjing, China). )

1, a common term for calendar calculation and calendar preparation rules.

Zodiac: it is the coordinate value used to determine the position of celestial bodies on the celestial sphere in the ecliptic coordinate system. In this system, the celestial sphere is divided into two hemispheres by the ecliptic plane. When the sun moves to the ecliptic at 0 degrees, it is the vernal equinox, the ecliptic at 90 degrees is the summer solstice, 180 degrees is the autumnal equinox, and 270 degrees is the winter solstice. Shuori: The day when the moon moves between the earth and the sun is called Shuori. Pingshuo: calculated by the average length of the moon, regardless of the inequality between the sun and the moon; Disadvantages: "The day containing the real" new moon "may sometimes appear on the last day of the previous month ("dark day ",29th or 30th), and sometimes on the second day of junior high school". Deciding the new moon: the inequality between the sun and the moon is taken into account in the calculation, and the day of the real "new moon" is taken as the beginning of each month. Mean air: The uneven motion of the sun on the ecliptic is not considered in the calculation, and the number of days between two solar terms of mean air is 15.22 days. Settlement: Considering the uneven movement of the sun on the ecliptic, the days between the two solar terms are different, the short one is only 14 days, and the long one is 16 days. Winter solstice: the day when the winter solstice is handed over is called winter solstice. The winter solstice must be in the second month: set the day of the winter solstice or the day before the winter solstice as the "starting point" of the first day of the second month (note: the starting point is different from fortune telling). Jian Zheng: In the first month, Jian Zheng is "Xia Zheng: Yin Jian in the first month of the summer calendar [the second month 1 1 month]; Andrew: The first month of the lunar calendar is ugly [February 65438+ February], and the Lu calendar is the same as the lunar calendar; Zhou Zheng: The Zhou calendar (Zhou Dynasty calendar) was built in the first month [February is the first month]; Qin Zheng: The Zhuan Xu calendar of the Qin calendar was established in the first month [February]. Leap: Lunar calendar 1 month is 1 full moon, and the average number of days in each month is ≈29.53059 days, and lunar calendar1February is ≈354.367 days; However, the return year of 1 is ≈365.2422 days, so the lunar year is ≈ 10.866 days, and the lunar year is ≈2.7 177 1 month. If we don't adjust it, winter and summer will be reversed decades later. In order to make the average number of days in the lunar calendar equal to the tropical year, leap months must be set up. Please look at the calendar rules of the lunar calendar in previous dynasties.

2. Calendar rules of past dynasties:

Solar terms: There are 24 solar terms in a year, which are calculated in terms of flat gas before the Qing Dynasty (A.D. 1644) and constant gas after the Qing Dynasty (A.D. 1644). Definition of a day: The earth rotates once a day. Among them, the hour when the sun is farthest from the horizon is the first hour of the day. Then, the time is within an hour around zero now. So, in this way, a day in the summer calendar begins at 23:00 today. Monthly policy rules: Shuori is the starting point of each month (the first day); There are as many days as there are from the first day of the first month to the second day. The big moon has 30 days and the small moon has 29 days; Pingshuo was used before the Tang Dynasty (AD 6 19), and Dingshuo was used after the Tang Dynasty (AD 6 19). Year policy and leap rule: the winter solstice must be in the second month (Andrew 1 1 month), the last winter solstice (Andrew lunar calendar 1 1 month) and the next winter solstice (second month \ lunar calendar1/kloc-0). From the winter solstice in 2033 to the winter solstice in 2034, a leap needs to be set. The first neutral month (1 1 month) from the winter of 2033 to the future is 1 month from the winter of 2033, which is designated as a leap month. It is just after the winter solstice (sub-month [165438+ 10]), so it is called leap sub-month (leap 165438+ 10).