How to calculate leap month? What are the rules?

Leap month is a kind of calendar leap, which means that one month is added every two to three years in the lunar calendar. In the lunar calendar, the moon revolves around the earth. In the lunar calendar, the length of the first month of the lunar calendar is 29.5306 days, which is the average of one month. The whole year is 65438+February, which is 10.88 days less than 365.2422 days in the tropic year. The product is a leap. So leap for one month every three years, two months every five years and seven months every nineteen years. The following are two calculation methods:

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.

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. The leap month was cloudy that year.

The birth of leap month

Leap moon refers to a phenomenon in the lunar calendar. The lunar calendar arranges the big moon and the small moon according to the full moon, that is, the full moon. The length of the full moon is 29.5306 days, which is the cycle of the moon's profit and loss.

According to the lunar calendar, the big moon has 30 days and the small moon has 29 days, so a year 12 months has 354 days, and the lunar months have no seasonal significance, so 12 months constitute the Han calendar, with a length of 354.3672 days, which is less than the tropical year of 365.242210.82.

In this way, there is a difference of 1 1 day in a year, and the date will be reversed with the seasons only after the lunar calendar 17. For example, after the seasons are reversed, the new year will be spent in summer, which naturally cannot meet the needs of agricultural production. In order to overcome this problem, our ancestors, on the basis of astronomical observation,