About the lunar calendar in China.

Lunar calendar is a traditional calendar adopted by China, also known as summer calendar, middle calendar and old calendar. Some people call it the lunar calendar. It uses the strict lunar cycle to determine the month, and sets the leap month to make the average length of a year close to the tropic year, which has the attributes of lunar month and solar year, so it is essentially a kind of yin-yang calendar. In the lunar calendar, the date when the sun and the moon meet (the ecliptic is equal) is the first day of the month, that is, the first day. The average length of the first month of the lunar calendar is about 29.53059 days, so some months are 30th. Call the moon big; Some months are the 29th, called abortion. The date of the beginning of the month is calculated according to the position of the sun and the moon, not mechanically arranged. The lunar calendar takes1February as a year, ***354 or 355 days, which is different from the tropic year 1 1 day. Therefore, coordination is achieved by inserting 7 leap months every 19 years. The arrangement of leap month is determined by the 24 solar terms.