Observing the Heavens. The Egyptians studied the movements of heavenly bodies for religious reasons. Cycles of astronomical phenomena were used to measure time and thus allowed the Egyptians to perform rites on the correct day and at the precise hour. By observing the movement of a particular star, especially its disappearance for a period and return to a starting point, the Egyptians could calculate when a festival for a particular god should be celebrated. Egyptian astronomers could predict the time of sunrise and the appearance of certain stars associated with deities. These observations allowed a ritual to start at exactly the correct time. The Egyptian descriptions of these observations and calculations were expressed in mythological language, and noticeable changes in their methods and descriptions can be traced through their long history.

Prehistoric Astronomy. Evidence from Nabta in the Western Desert...