Who wrote the 24 solar terms?

As early as the Spring and Autumn Period and the Warring States Period, the sundial was measured by earth gauge in ancient China (that is, a pole was erected on the plane to measure the length of the midday sun shadow) to determine the four solar terms: vernal equinox, summer solstice, autumnal equinox and winter solstice.

In a year, the shortest day of the shadow of returning to the earth at noon is the summer solstice, the longest day is the winter solstice, and the shadow with moderate length is the vernal equinox or autumnal equinox.

The Book of History in the Spring and Autumn Period recorded the solar terms.

There were only four solar terms in Shang dynasty, while there were eight solar terms in Zhou dynasty.

The names of the twenty-four solar terms first appeared in Liu An's "Instructions of Huainan Tian Zi" in the Western Han Dynasty, and the concepts of Yin and Yang, four seasons, eight places, twelve degrees and twenty-four solar terms were also mentioned in the preface to Historical Records Taishi Gong.