Why is the lunar calendar so accurate? So it's in season! Why hasn't it changed after all this time?

The twenty-four solar terms invented by our ancestors have been listed in the world intangible cultural heritage list, which is called the fifth invention of China, showing the wisdom of our ancestors.

The earth goes around the sun once, that is, the moon goes around the earth 12 times, 1, and a year is 12 months, with only 354 days. Compared with the real number, it is about 1 1 day, and it is accumulated to three years and 33 days. Therefore, a leap month must be set every three years, and there are still three or four days. The wet month is the month without festivals, the leap year is the year with leap months, the leap year is 13 months, and the average year is 12 months.

There are 24 solar terms in a year and a festival every month. No two solar terms are separated by an average of 30 days and 10, while the number of days in a lunar month is 29 and a half days. Therefore, in every 34 months, there will be only festivals and no festivals in two months, that is, a month with festivals and no festivals is a lunar leap month, and a month with festivals and no festivals is not a leap month.