As early as the ninth century, Muslim astronomers started refining the Ptolemaic astronomy which, by this time, had been fully adopted as the framework of their research. Already, in the early part of this century, refinements were based on improved observational techniques, and included a variety of phenomena such as the length of the seasons, the solar equation, mean motion parameters, and many others.

This study provides a detailed description of ways in which Muslim astronomers handled the Greek astronomical legacy, reassessed its cultural and philosophical implications in light of their religiously-inspired world view, and proposed to modify it.