Was the first to propose the sun was at the sun of the universe but many forget he proposed this first after Copernicus did even though he proposed this 1750 years earlier
He also attempted to measure the distance between the earth and sun and the earth and moon. His results were very off but that is because he didn't have the technology needed to find the distance
He invented the Ptolemaic system which predicted the movement of the stars,sun, moon, and planets
His model was biased off of a universe that was centered around the earth and the Ptolemaic model is one of the longest upheld scientific theories in history: it was the cornerstone of astronomy for 1,500 years.