How long can Chinese and solar birthdays be on the same day?

19 is a year that people can observe and experience in their average life span, and it is a "recent coincidence" between the Gregorian calendar and the Lunar calendar.

It is said to be "recently coincident" because some solar calendars and lunar calendars of 19 are completely coincident, and some are one day apart.

The so-called "twenty-four solar terms" were called "Qi" in ancient times. In order to distinguish, every month, the front is called "solar terms" and the back is called "gas". In primary school mathematics, in 19 calendar year, there should be 228( 12× 19) solar terms and 228 neutral terms. However, the lunar calendar 19 will have 235 new months, and 19 will have 7 leap months, because the lunar calendar defines a month without breath as a leap month.

This law was discovered in the Spring and Autumn Period of our country. The operation of Copernicus system is also the result. Zu Chongzhi's calculation is "39 1 year 144 leap", which is more accurate. Modern time service and calendar calculation are more accurate, and there will be "leap second" as fine-tuning. In any case, the solar calendar and the lunar calendar overlap once at 19, which is almost accurate and can be used for reference.