What is the main content of Kaiyuan Zhan Jing?

This book comprehensively compiles the achievements of China's ancient theory of the universe, a large number of records and divination judgments about celestial bodies, astronomical phenomena and meteorological changes, as well as the basic data of 29 calendars such as Indian Nine Calendars and Linde Calendars in the early Tang Dynasty and other astrological documents. This is a veritable astrological classic. In the book, astronomical knowledge is integrated with the inductive thought between man and nature. The division of stars in the sky corresponds to the division of positions and names of various regions on the ground. The normal movement and abnormal changes of the sun, the moon, the five stars, and the stars such as Liu, Comet, Demon (a variant or nova of Comet) and Guest (nova), as well as the astronomical phenomena of stars, are all related to the fortunes of emperors, countries and social life, which shows that China's astrology is a prediction and interpretation of the fate and military affairs of all dynasties.