The origin of solar terms in winter solstice

1, winter solstice, is one of the "24 solar terms". During the period of Emperor Wu of the Han Dynasty, twenty-four solar terms were absorbed into the calendar as a supplement to the calendar guiding farming, and the division of solar terms adopted the method of "balancing qi" (that is, the average time method).

2. The "flat gas method" uses photogrammetry to determine that the days in the Yellow River basin are as short as the winter solstice, divides the dates between the winter solstice and the next winter solstice into twelve equal parts, which are called "neutral gas", and then divides the dates between adjacent "neutral gas" into equal parts, which are called "solar terms"; On average, there is a "neutral gas" and a "solar term" every month, which are collectively called "24 solar terms".