What does the star map in "Choose the Sky" refer to? (novel or TV series)

The TV series "The Choice of Heaven" Chen Changsheng went to Joo Won? to look for the star map, and the Saint King also wanted to find the star map. So what is choosing a star map and what is its use? In the play, Chen Changsheng, led by Xun Mei and Chen Changsheng, came to the place where Du Fu paid homage to the monument. Sure enough, he saw a picture full of stars, that is, a star map, which was mysterious and extremely profound. In order to win a chance to change his life, Chen Changsheng put all his thoughts into this painting.