Which dynasty did 24 solar terms belong to? In China, it is legally a year?

As early as the Spring and Autumn Period, four solar terms were set, namely, mid-spring, mid-summer, mid-autumn and mid-winter. After continuous improvement and perfection, by the Qin and Han Dynasties, the 24 solar terms had been completely established.

In ancient China, the sundial was measured by earth gauge, and the longest shadow was defined as "solstice" (also known as long day to day, long day to day, summer to day), and the shortest shadow was "short day to day" (also known as short day to day and winter to day). One day in spring and autumn is the same length of day and night, which is designated as "vernal equinox" and "autumnal equinox". There were only four solar terms in Shang dynasty, but it developed to eight in Zhou dynasty and was completely established in Qin and Han dynasties. In BC 104, the taichu calendar written by Deng Ping officially set 24 solar terms in the calendar, and defined the astronomical position of the 24 solar terms.

The names of the twenty-four solar terms first appeared in Tian Zi Xun of Huainan, and the concepts of Yin and Yang, four seasons, eight places, twelve degrees and twenty-four solar terms were also mentioned in Preface of Historical Records Taishi Gong. During the period of Emperor Wu of the Han Dynasty, Luo compiled solar terms into the calendar, stipulating that the month without neutral gas was the last month of leap month.

Each of the 24 solar terms corresponds to a certain position reached by the sun every time it moves 15 on the ecliptic. The twenty-four solar terms are divided into 12 solar terms and 12 solar terms, which correspond to each other one by one. The 24 solar terms reflect the annual apparent movement of the sun, so their dates are relatively fixed in the solar calendar. The first half of the solar term is 6 days, the second half is 28 days, and the second half is 23 days, with a difference of 1 ~ 2 days.

The naming of the twenty-four solar terms reflects three seasons, climate phenomena and climate change. The reaction seasons are beginning of spring, Spring Equinox, Long Summer, Summer Solstice, beginning of autumn, Autumn Equinox, beginning of winter and Winter Solstice, also known as Eight; The response to climate phenomena is surprised, bright, full and mans; Rain, Grain Rain, little summer, big summer, early summer, white dew, cold dew, first frost, light snow, heavy snow, slight cold and severe cold are the responses to climate change.

As early as the Spring and Autumn Period and the Warring States Period, people in China had the concepts of Solstice in the South and Solstice in the North. Subsequently, people divided the year into 24 equal parts according to the natural phenomena such as the running position of the sun and the moon at the beginning and middle of the month, the weather and the growth of animals and plants. And give each equal part a proper noun, that is, twenty-four solar terms. By the end of the Warring States Period, solar terms had eight names: beginning of spring, Equinox, Long Summer, Summer Solstice, beginning of autumn, Equinox, beginning of winter and Winter Solstice. These eight solar terms are the most important of the 24 solar terms. These eight solar terms mark the change of seasons and clearly divide the four seasons of the year. Later, when the book Huai Nan Zi was published, the names of the 24 solar terms were exactly the same as those of the modern ones.