Tenth Century AD

For early Chinese rulers, observing the heavens and communicating the passage of time to the people were divine obligations  

This picture shows a tenth century star map of a group of constellations known then to the Chinese as the Purple Enclosure. The big dipper is easily recognizable in this map. This map was based solely on naked eye observations.

In 1054 AD, the Chinese also observed and recorded the first Supernova explosion whose remains we know today as the crab nebula.