In ancient times, how to calculate the handover time of solar terms, such as in beginning of autumn? Or is it not accurate enough?

The lunar calendar has an ancient history and is a kind of lunar calendar. The solar calendar is a pure Gregorian calendar, so the lunar calendar is more complicated than the Gregorian calendar.

The concept of Gregorian calendar year cannot be directly applied to lunar calendar year.

Ancient times were divided into years and years. They are similar, but unequal. The concept that the ancient year is equal to the modern tropical year.

Beginning of spring solar terms are the nodes that divide a year, not the lunar year.

Lunar year is a node based on the length of the year and the phase of the moon.

Beginning of spring is the dividing line of ancient years, not years (years and years are two different concepts), and it has nothing to do with the moon phase.

A year must be the first day of a month, and the span of a year should be close to one year, which has a strong relationship with the moon phase.