How did the vernal equinox solar terms come from?

1. The phenological phenomenon corresponding to the ancient Yellow River Basin is "birds arrive, thunder rises, and electricity rises" (see "Nongsang Tongzhi"), which means swallows fly, thunder rises, and lightning rises. At this time, the overwintering crops in most parts of China entered the spring growth stage. Central China agricultural proverb: Wheat rises at the vernal equinox, and every moment is worth a thousand dollars. The vernal equinox is also a traditional festival. In the Zhou dynasty, there was a ceremony to worship the sun at the vernal equinox.

2. The vernal equinox is called "Japan-China", "Day and Night Equinox" and "Midspring Moon" in ancient times. "Li Mingshi Yi" said: "The dividing line, the turn of Huang Chi, the sun stops here, and the day and night are equally divided." It means: the meaning of the vernal equinox, first, refers to the equal division of day and night, each day and night is 12 hour; Second, in ancient times, it was spring from beginning of spring to long summer, and the vernal equinox happened to be in the three months of spring, and spring was equally divided.

The vernal equinox is also a festival and ritual celebration. The ancient emperors had a system of offering sacrifices to the sun in spring and the moon in autumn. The ritual of the Zhou Dynasty was to offer sacrifices on the altar.