Ten heavenly stems and twelve earthly branches are collocated in turn to form sixty basic units, and they cooperate with each other in a fixed order to form the chronology of the stems and branches. Heavenly stems and earthly branches's invention had a far-reaching impact, and heavenly stems and earthly branches still uses it today, which is used in calendar, art number, calculation, naming and so on.
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Stem and astrology:
According to the knowledge of modern astronomy, we can know that the 28 stars on Sunday are composed of stars, which are very stable in astronomy. Their relative positions have remained unchanged for thousands of years or even longer, and their influence on the earth is relatively stable.
The earth and other planets in the solar system revolve around the sun constantly, while the whole solar system hovers in the Milky Way at the same position relative to the Polaris (purple and micro stars). Because of the movement of the sun, the moon and the five stars, the positional relationship between the stars changes, which in turn changes the influence of specific stars on the earth and everything on the ground. So the ancients predicted good or bad luck by observing the sky at night.
Among the natural features of the five elements of A, B, C, D, E, Ji, G, Xin, Man and Ghost, A and B carry qi, C carries fire, E carries humidity, dryness and cold, which shows that the qi of the five elements in the sky changes gradually according to the mutual development process of the five elements.