The lunar calendar is a lunar calendar. What is the reason?

The lunar calendar is a calendar currently used in China in parallel with the Gregorian calendar (Gregorian calendar). People are accustomed to calling it the "lunar calendar", but it is actually a type of lunisolar calendar, that is, the summer calendar, and is not a true "lunar calendar" . There are twelve months in an ordinary year, the big month has thirty days, the small month has twenty-nine days, and the whole year has 354 or 355 days (which month is bigger and which is smaller in a year varies from year to year). Since the number of days in each year is about eleven days less than that of the solar year, the method of setting leap months is used to make the average number of days in these years as close as possible to 365.2422 days. Since there are 12.368 synodic months in a tropical year, 368/1000=46/125, forty-six leap years should be set in 125 years. However, because it is too complicated to set leap years, it is calculated that 7/19 is the most It is close to 0.368, so generally, there are 7 leap months in 19 years, and the year with leap months has 383 or 384 days in the year. According to the position of the sun, a solar year is divided into twenty-four solar terms to facilitate agricultural planting and other activities. The chronology is based on the combination of heavenly stems and earthly branches, and the sixty-year cycle begins again and again. This calendar is said to have been created in the Xia Dynasty, so it is also called the Xia calendar. Also called the old calendar. Because the twenty-four solar terms are of great significance to agricultural production, people often refer to the lunar calendar as the "lunar calendar." However, the twenty-four solar terms should be determined based on the position of the sun on the ecliptic and should belong to the solar calendar. Therefore, it is inappropriate to call the lunar calendar a lunar calendar. In astronomy, the Gregorian calendar refers to a calendar mainly arranged according to the annual movement of the sun. Its year has about 365 days. The solar calendar is based on the cycle of the sun's direct point. Its average calendar year is a tropical year. There are two types of calendar years, one is an ordinary year and the other is a leap year. The leap year is only one day different from the ordinary year. The commonly referred to as the Gregorian calendar, the Gregorian calendar, is the current Gregorian calendar. Since there are 365.242199174 days in a year, not exactly 365 days, there is a leap year every four years, that is, February has an extra 29th day. After a leap year of four years, it has been corrected to 365.25, but there is still an error, so every hundred years a leap year is subtracted, that is, there are no leap years in 1700, 1800, 1900, etc., and it is 365.24 after correction. Finally, a leap year is added back every four hundred years, that is, there are leap years in 1600, 2000, 2400, etc., and the final correction is 365.2425. There is still an error of 0.0003, and it takes about 3000 years to have an error of one day, so it is already very accurate. The solar calendar, also known as the Gregorian calendar, is a calendar based on the movement cycle of the earth revolving around the sun. The calendar year of the solar calendar is approximately equal to the tropical year, and there are 12 months in a year. This "month" actually has nothing to do with the synodic month. The months and dates of the Gregorian calendar are in good agreement with the position of the sun on the ecliptic. According to the dates of the Gregorian calendar, the changes in cold and warmth in the four seasons can be clearly seen in a year; but in each month, the moon's new moon cannot be seen. , Wang, two strings. The Gregorian calendar currently used in the world is a solar calendar, with 365 days in an ordinary year and 366 days in a leap year. There is a leap year every four years, one less leap year every hundred years, and another leap year in the fourth hundred years, that is, there are 97 leap years every four hundred years. The average length of the Gregorian calendar year differs from the tropical year by only 26 seconds, and it would take 3,300 years to accumulate just one day. The Gregorian calendar currently used in the world is the solar calendar that people are most familiar with. This calendar is steeped in the civilization created by mankind over thousands of years. It was learned by the ancient Romans from the Egyptians and spread throughout the world with the expansion of the Roman Empire and the rise of Christianity. In astronomy, the lunar calendar mainly refers to the calendar arranged according to the lunar phase[1] cycle. The moon orbits the earth once (using the sun as the reference object, the actual moon orbits more than once) as one month, that is, the synodic month is used as the basis for determining the calendar month, and a year is a calendar of twelve calendar months. In agricultural meteorology, the lunar calendar is commonly known as the lunar calendar, Yin calendar, ancient calendar, and old calendar, and refers to the summer calendar traditionally used in China. In astronomy, it is believed that the lunar calendar is actually a lunisolar calendar. The calendar set based on the apparent motion of the sun is called the "solar calendar", or "solar calendar" for short; the moon is the "lunar calendar", and the calendar set based on the apparent motion of the moon is called the "lunar calendar", or "lunar calendar" for short. . The lunar calendar determines the moon based on the movement rules of the moon: the orbit of the moon is called the ecliptic. The ecliptic and the ecliptic are two great circles on the celestial body, intersecting obliquely at five degrees and nine minutes. The moon orbits the earth once and appears and disappears on both sides of the ecliptic. times, twenty-seven days, seven hours, forty-three minutes, eleven and a half seconds, which is the time it takes for the moon to make one revolution, which is called a "sidereal month". Only when the moon orbits the earth, the earth's position also changes due to its revolution, advancing more than 27 degrees, and the moon travels 13 degrees and fifteen minutes every day, so the moon self-conjuncts, completes a full circle around the earth, and returns to the new moon. The synodic moon actually takes 12:44:2.8 on the 29th, which is called the "lunar lunar month". According to custom, a month refers to the lunar lunar month. The first day of each month is called Shuo, and the last day is called Hui. The fifteenth, sixteenth or seventeenth day of the lunar calendar is called Wang, and the day after Wang is called Jiwang, so the New Year's Eve of the Spring Festival does not fall on the same day every year. The basis of the lunar calendar is the "Hunting Year" and the "Synozygous Moon". The "tropical year" is the time it takes for the sun to pass through the vernal equinox twice in succession, which is 365.2422 days (365 days, 5 hours, 48 ??minutes and 46 seconds). "Synodial" is the time between two consecutive new moons or two full moons of the moon, that is, 29.5306 days (29th, 12 hours, 44 minutes and 3 seconds).

Since the 12 synodic months only have 354.3672 days, which is more than 10 days different from the 365.2422 days of the "Return of the Year", the cumulative difference becomes a leap month. As early as the Spring and Autumn Period of 500 to 600 BC, the Chinese calendar adopted the arrangement of seven leap months in nineteen years. However, the calculation methods of the Chinese lunar calendar, the Tibetan lunar calendar and the Korean lunar calendar are different, and generally there is a difference of one or two days. The lunar calendar dates are calculated based on the waxing and waning of the moon. The new moon is the first day of the lunar month, the full moon is the fifteenth day (the big moon is the sixteenth day), and the twilight moon is the twenty-ninth day (the big moon is the thirtieth day). day). However, current timekeeping is usually expressed using solar calendar dates. If you want to convert solar calendar dates to lunar calendar dates, you can use the following two methods: One is to check the "New Perpetual Calendar". For example, what day in the lunar calendar is June 8, 1984? Turning to the perpetual calendar, June 10th is the eleventh day of the lunar calendar, and then June 8th is the ninth day of the lunar calendar. Second, you can use the formula to calculate the lunar date: Assume: AD year - 1977 (or 1901) = 4Q + R, then: lunar date = 14Q + 10.6 (R + 1) + date ordinal number in the year - 29.5n (Note: Q, R, n are all natural numbers, R<4) Example: The lunar calendar date of May 7, 1994 is: 1994-1977=17=4×4+1 Therefore: Q=4, R=1 Then: the lunar calendar date of May 7 is: : 14×4+10.6(1+1)+(31+28+31+37)-29.5n=204.2-29.5n Then divide 204.2 by 29.5 to get the quotient 6...27.2, 6 is is the n value, and the remainder 27 is the twenty-seventh day of the lunar calendar.