birthdates, abbreviated as eight characters, refers to the calendar date when a person was born; On the year, month, year, and day, there were * * * four pillars, each with two words, which was called * * * eight words. Birthdates occupies an important position in the folk beliefs of the Han nationality, and ancient astrologers of the Han nationality calculated the fate of people accordingly. The eight-character prediction has been developing continuously in practice. From the three pillars in Li Xuzhong to the four pillars in Xu Ziping to the four pillars of the solar law and the moon law, every step of the progression contains the hard work of scholars and social practice activists in past dynasties.
In order to get the correct birth time, the ancient Han people thought that the sundial instrument was the most accurate measurement during the day. When the clock time is the artificial average time and regional standard, we must calculate the "apparent solar time difference" according to the solar terms (solar ecliptic) and the "local longitude time difference" according to the place of birth, so as to get the real astronomical time of birth.
in the almanac, there are basically the branches of the year and the branches of the day, while the branches of the month and the time can be calculated according to the formula.