What is the origin of the vernal equinox solar terms?

1, vernal equinox, March 20th or 2 1 in Gregorian calendar every year, when the sun reaches 0 degrees (vernal equinox). The length of day and night is average, just half of the 90th day of spring, so it is called "vernal equinox". On the vernal equinox, the sun shines directly at the equator, and day and night are almost equal. Then the direct sunlight position gradually moved northward, and the days were long and the nights were short. The vernal equinox is an important solar term, which not only has astronomical significance: the northern and southern hemispheres are equally divided day and night; Climatically, there are also obvious characteristics. During the spring equinox, China has entered a beautiful spring scenery except the Qinghai-Tibet Plateau, Northeast China, Northwest China and North China. On the vast land, willows are green, Fei Ying grass grows, wheat jointing and rape blossoms are fragrant.

2. "Twenty-four solar terms": (Gregorian calendar) In the middle of February, the minute is also half, which is 90 days and a half, so it is called minutes. Autumn is synonymous. "Han Dong's book" Spring and Autumn Stories Up and Down of Yin and Yang ":"As for the mid-spring moon, Yang is due to the east and Yin is due to the west, which is called the vernal equinox. The vernal equinox is half yin and half yang, so it is cold and summer day and night. " The corresponding phenological phenomenon in the ancient Yellow River basin is "the arrival of a mysterious bird, the thunder and the electricity" (see "Nongsang Tongzhi"). At this time, the overwintering crops in most parts of China entered the spring growth stage. A farmer's proverb in central China says, "Wheat rises at the vernal equinox, which is a worthwhile moment." The vernal equinox is also a traditional festival. In the Zhou dynasty, there was a ceremony to worship the sun at the vernal equinox. Book of Rites: "Altar." Confucius' Ying Da Shu: "Also called the vernal equinox." This custom has been handed down from generation to generation. Pan Qingrong won Ji Sheng at the age of Emperor Jing: "The vernal equinox and autumn are a grand ceremony of the country, and scholars should not worship it." Around the Spring Equinox in Qing Dynasty, ministers in the palace paid homage to ancestral temples, and aristocratic families also paid homage to ancestral temples every day. The Chronicle of Jingchu in Liang Zonggu of the Southern Dynasties records: "On the day of the vernal equinox, people planted fire-fighting grass on their houses. If there is a blackbird, the chicken crows first, and the people wait for it and enter the field, thinking that they will wait for it. " In the Ming Dynasty, planting trees in Zichuan, Shandong Province, brewed spring wine to cool off the heat. "Wenshui County Records" contains: "On the vernal equinox, the wine is cold and the flowers move."