Ptolemy

Claudius Ptolemy was a Greco-Roman mathematician working in the second century AD who wrote roughly a dozen scientific treatises. Three survived to reshape medieval knowledge: the Almagest, his astronomical work that presented the only mathematically rigorous geocentric model of the solar system; the Geography, a systematic treatment of maps and the known world; and the Tetrabiblos, where he tried to reconcile horoscopic astrology with Aristotelian physics. The Catholic Church later promoted his astronomy, and Byzantine and Islamic scholars copied his works through late antiquity and the Middle Ages. But the math was dense - most readers relied on abridged summaries rather than engage the original calculations. His system held until it didn't.