Medieval astronomy refers to the study of celestial bodies and their movements during the Middle Ages, roughly from the 5th to the 15th century. Scholars built upon the knowledge of ancient civilizations, particularly the Greeks and Romans, using tools like the astrolabe and armillary sphere to observe the stars and planets. They aimed to understand the universe's structure, often blending scientific inquiry with religious beliefs. During this period, notable figures such as Alfred the Great and Copernicus contributed to astronomical knowledge. The Ptolemaic system, which placed the Earth at the center of the universe, dominated medieval thought until the Copernican Revolution shifted perspectives toward a heliocentric model.