Hello, everyone. How to determine which months of the lunar calendar have only the 29th and which months have the 30th?

The lunar calendar is a monthly calendar, and the moon revolves around the earth in January, so the lunar year is very different from the astronomical year. The lunar calendar has twelve lunar months, 353, 354 or 355 days, which is about 1 1 day less than astronomy. In order to keep pace with the astronomical year, it is necessary to set up a leap year every three lunar years. There are thirteen months in a leap year, and the added months are called leap months.

Lunar year is determined by 24 solar terms, and solar terms are determined by the sun. The first solar term of the lunar calendar is called rain, which is set on the day when the sun angle is 330 degrees. The other 23 solar terms are set on the day when the sun angle changes 15 degrees. Among the 24 solar terms, 12 is the main solar term: rain, vernal equinox, Grain Rain, summer fullness, summer solstice, summer heat, autumn equinox, first frost, light snow, winter solstice and severe cold.

There are two rules for determining the leap month in the lunar leap year:

One: The winter solstice must fall on the winter moon of the lunar calendar. If it doesn't fall, one month before the twelfth lunar month will become a leap year.

Two: If it is a leap year, the first month after the winter month without major solar terms will be designated as a leap month. Leap month uses the name of last month.

We all know that the earth's orbit around the sun is an ellipse, and the sun is at a focus of the ellipse. In a year, the distance between the earth and the sun is near and far. When the earth is far away from the sun, it moves slowly around June in Gregorian calendar, so the interval between the two gases is longer, exceeding 3 1 day at the longest. According to the average length of 30.5 days in the past, there is a great possibility that this month does not include major solar terms, and there is a great possibility of a leap month. So there are more opportunities in April, May and June, and fewer opportunities in July, August and September. After beginning of winter, the earth runs fast and the air interval is short, the shortest is only a little more than 29 days, which is shorter than one month in the lunar calendar. Therefore, it is even more impossible for 1 1 month and twelfth month not to include major solar terms, and it is impossible for the first month not to include major solar terms, so there is no leap in the first month.