What did muslim astronomers discover

The first major Muslim work of astronomy was Zij al-Sindhind by al-Khwarizmi in 830. The work contains tables for the movements of the Sun, the Moon and the five planets known at the time. The work is significant as it introduced Ptolemaic concepts into Islamic sciences.

It can provide a social code to protect each citizen's future economical earnings. and then obviously defending the country from invading countries.