This set of star charts shows the whole starry skies visible in different seasons in the 40 ° north latitude region. The outer circle of the star map is marked with East, West, North and south directions. The innermost circle is the horizon of the observation site, and the center of the star map is the zenith of the observation site. When using, you can lift the star map so that the directions marked on the map are consistent with the actual directions. Then you can follow the map and learn to identify the constellations step by step starting from recognizing the bright stars. Stars brighter than 4 magnitude and a small number of stars with brightness of 5 magnitude are depicted in the figure. Bright stars are marked with Chinese star names. Some well-known deep space objects are also reflected.