What are these two calendars? How are these two calendars made?

It is divided into lunar calendar and solar calendar, among which lunar calendar is also called ancient calendar and Han calendar.

In astronomy, the lunar calendar is formulated according to the moon phase cycle, and the moon's orbit around the earth is taken as January, that is, the first month of the lunar calendar is used as the basis for determining the calendar months, and a year is twelve calendar months.

Gregorian calendar is the international Gregorian calendar. The Gregorian calendar is customized based on the time that the earth revolves around the sun for one year, ***365 days, 5 hours, 48 minutes and 46 seconds. A year is divided into 12 months, big month 3 1 day, small month 30 days, and February only has 28 days. An average year is only an integer of 365 days, not a mantissa. The mantissa of four years accumulated to about *** 1 day, and it was added to February of the fourth year. This year is called leap year, so February in leap year has 29 days.

Extended data:

The development of ancient calendar in China:

From the history of calendar development, all countries with ancient cultures, such as Egypt, Babylon, India, Greece, Rome and China, initially used the lunar calendar.

After the agriculture in ancient countries developed slowly, it was found that the seasons and climate of agriculture were not comparable to the lunar calendar, January, spring, summer, autumn and winter. In order to solve the contradiction between the lunar calendar and the solar calendar, there are two methods in ancient times: one method is to abandon the moon's gain and loss in the lunar calendar as a method of calculating months, and divide a year into 12 months, with 365 days in a normal year, 366 days in a leap year and 4 years in a leap year. This is the method adopted by western Rome in 46 BC. Another method is to find the least common multiple of the days in the solar year and the days in the lunar month.

Although the above two methods can reconcile the lunar calendar and will not be reversed in winter and summer, the solar terms can still differ by one month in a year, which is still not accurate enough for agricultural operation arrangement. So at the end of the Warring States period, 24 solar terms were established, which complemented the lunar calendar. It was not until the Eastern Han Dynasty that it was founded 72 times a year. This is the development of our ancient calendar.

Baidu encyclopedia-lunar calendar