How is the solar term calculated?

As early as the Eastern Zhou Dynasty, the Spring and Autumn Period and the Warring States Period, the working people of the Han nationality had the concept of "the sun facing the sun in the south" and "the sun facing the sun 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.