Why are the 24 solar terms solar calendar?

China has 24 solar terms in the lunar calendar. Many people describe the lunar calendar in China as the lunar calendar, so they also think that the 24 solar terms belong to the lunar calendar. In fact, this is a wrong understanding. The lunar calendar is not a lunar calendar, but a lunar calendar, and the 24 solar terms are part of the solar calendar.

Since the Western Han Dynasty in China, people have divided the tropical year into 24 equal parts and set 24 solar terms. In the Tang dynasty, people found that the speed of the sun running on the ecliptic was uneven, so they divided the ecliptic into 24 parts from the vernal equinox, each of which was 15. As a solar term, the sun runs from west to east on the ecliptic 15.

This method of dividing the 24 solar terms is more scientific and reasonable, and it has been used ever since. Since the years in 24 solar terms and Gregorian calendar reflect that the sun travels once on the ecliptic, there is a strict correspondence between the dates in 24 solar terms and Gregorian calendar.

Twenty-four solar terms are a unique creation of ancient people in China. People can arrange various agricultural activities according to the solar terms. There are 12 "neutral qi" in the 24 solar terms. Starting from the vernal equinox, every other solar term is a neutral gas, which is expressed in blue in the table.