What does leap month mean? The origin of leap month.

Lead: Generally, there are only 12 months in the lunar calendar, but there will be leap months in some years, with 13 months. So what does leap month mean? Many people don't know. So let's talk about the reason of leap month today. In fact, simply speaking, the lunar year and the tropic year are different.

What does leap month mean?

Leap moon refers to a phenomenon in the lunar calendar. The lunar calendar arranges the big moon and the small moon, that is, the moon, according to the full and short moon. The length of a moon is 29.5306 days, which is the cycle of the moon's profit and loss. According to the lunar calendar, there are 30 days for the big moon and 29 days for the small moon, and a year is 12 months * * 354 days. The lunar month has no seasonal significance, so just after 17, the date of the lunar calendar will be reversed with the seasons. For example, one year's New Year is spent in the snow, and after 17, the vermicelli will be shaken to celebrate the New Year. The use of such a calendar naturally cannot meet the needs of agricultural production, so the lunar calendar in China has been in parallel with the 24 solar terms since the Qin and Han Dynasties, and the 24 solar terms are used to guide agricultural production.

Twenty-four solar terms can be divided into two groups: "solar terms" and "middle qi": the ancients regarded every 300 meridian from slight cold as a solar term; From the winter solstice, every 300 meridian is a neutral gas, and there are 12 solar terms and 12 neutral gas in a year. 12 solar terms divide a year into 12 months, and each month has a solar term and a neutral atmosphere. Solar term is the starting point of solar term month; Zhongqi is the midpoint of the festival. The traditional calendar in China does not adopt the method of day-to-day and month-to-month sequence and long-term arrangement of big month, small month, normal year and leap year, but emphasizes the calculation from year to month. The state sets up special institutions to calculate calendars.

(1) Set the date order according to the moon phase. It calculates the date and time of the conjunction of the sun and the moon one by one, and the first day of each month is the date of the conjunction; Determine the size of last month according to the number of days included in the second conjunction. If the interval between this new moon and the next one is 30 days, then this month is the big moon; If it is only once every 29 days, it is an abortion.

(2) Set the month order with neutral gas. First of all, the calendar month and leap month are distinguished by whether the calendar month is neutral or not. We know that there are 12 neutral gases in a tropical year, but it contains 365.2422 ÷ 29.5306 = 2.3682 satellites. After several calendar months of rotation, there must be a calendar month without neutral gas. "Han Shu Li Biao" contains: "The new moon cannot be seized, which is called leap moon". This month without neutrality is a leap month. When the previous calendar day is a few months, it is a leap month. For example, the leap month in 1984 appears after October of the old calendar, so it is called "leap October". Leap months are calculated, not fixed in the monthly order of the year. In addition to 1 1 month,1February and the first lunar month, leap month is possible, and it is the seventh leap month in the nineteenth year.

To sum up, leap year is a phenomenon in the solar calendar, which is fixed in February, 29 days longer than the normal year; Leaping moon is a phenomenon in the lunar calendar. This is a leap month. That year, there were 13 months in the lunar calendar, and that year was called leap month year. Leap Moon is 384 years old.

The difference between leap year and leap month

Probably many people think that "leap month" and "leap year" are the same meaning, but they are not. Although there is only one word missing, the meaning is far from the same.

What we usually call a "leap year" of 365 days a year is actually a rough figure, and the exact figure should be 365.2422 days. Then there are 365 days in a year, which is 0.2422 days different from the actual year, so four years later, it is nearly one day less than the actual year. In order to make up for this difference, the calendar stipulates that four years is a leap year, that is, a year divisible by four is a leap year. In addition, it is stipulated that every century year (the year with two zeros at the end) must be divisible by 400 to be a leap year, and other hundred years are not leap years, that is, "there is no leap in a hundred years". For example, 1996 is a leap year, and 2000 is also a leap year, but 1700 is not. The leap year in the solar calendar has 29 days in February, the leap day is February 29 and the leap year in the solar calendar has 366 days. In other words, February in a leap year in the solar calendar is not called leap February. It is said that "leap moon" is unique to yin and yang calendars (Han calendar, Tibetan calendar, etc.). ).

Leap years are divided into "solar calendar" and "lunar calendar"

The concepts of leap year in solar calendar and lunar calendar are different. The leap year we often talk about is actually the leap year of the Gregorian calendar.

A year with a leap day in the solar calendar is called a leap year.

A year with a leap month in the lunar calendar is called a leap year.

The leap years of the solar calendar and the lunar calendar do not coincide. For example, the lunar calendar 1995 and 200 1 are leap years, but the solar calendar is not. In 2000, the solar calendar was a leap year, but the lunar calendar was not.