Leap moon jingle formula

The mantra of leap month is "one cycle, 19 years and 7 months plus." Three years without leap, three years on both sides leap. Another two years, no leap month, and so on, another eight years. In the last three years, we will look forward to the coming year next week. "

Specifically, it means "leap in three years, leap in five years and leap in nineteen years". This is a unique leap year calculation method in the lunar calendar. Set a leap month every three years, two leap months every five years and seven leap months every nineteen years. This cycle continues.

Why did the ancients make such complicated and irregular calculation methods?

The ancients did this to make the lunar calendar more practical. Therefore, they combined the solar calendar with the lunar calendar and creatively invented the twenty-four solar terms. But the 24 solar terms are consistent with the solar calendar, that is, the time when the sun runs along the ecliptic is counted as one year. Then, according to the law of solar motion, the ecliptic plane is divided into 24 nodes to represent 24 solar terms. On the other hand, the lunar calendar counts the time for the moon to go around the earth as one month, and a year is 12 months.

Divisibility method:

This is the calculation method of leap year in Gregorian calendar. Specifically, divide the number of years by 4. If you get an integer, this year is a leap year. For example, AD 1992, divided by 4 is 498, then AD 1992 is a leap year.

How to leap? That is, an extra day in February is 29 days.

It should be noted that in this calculation method, when the number of years encountered is an integer multiple of 100, 400 must be removed. If you get an integer, this is a leap year of the century; If it is not an integer, it is not a leap year.