Solar term is a special festival in the trunk and branch calendar that expresses the change of natural rhythm and establishes "December construction" (monthly order). The 24 solar terms are: beginning of spring, Rain, Sting, Equinox, Qingming, Grain Rain, Changxia, Xiaoman, Mangzhong, Summer Solstice, Xiaoxia, Daxia, beginning of autumn, Early Summer, Bailu, Autumn Equinox, Cold Dew, Early Frost, beginning of winter, Light Snow, Heavy Snow, Winter Solstice, Slight Cold and Severe Cold.
Among the solar terms, beginning of spring, Jingzhe, Qingming, Changxia, Mangzhong, Xiaoshu, beginning of autumn, Bailu, Hanlu, beginning of winter, Daxue and Xiaohan are silver moon, Uzuki, Chen Yue, Mitsuki, Wuyue, Yue Wei, Shenyue, Youyue, Moon, Haiyue, Ziyue and Ugly Moon. In the historical development, the 24 solar terms have been incorporated into the lunar calendar and become an important part of the lunar calendar.
"Twenty-four solar terms" is the product of ancient farming civilization, and farming production is closely related to the rhythm of nature. It is a knowledge system formed by ancient ancestors who followed the farming season and realized the changing laws of time, climate and phenology in a year by observing the movement of celestial bodies. In ancient times, solar terms were established on the basis of "variable stars" (referred to by bucket handle), but now, solar terms are established on the basis of "the annual apparent movement of the sun" (the degree of the yellow meridian); Although the two methods are different, the cause of the struggle is that the earth revolves around the sun, so the intersection time of the two methods is basically the same.