The Roman scientist who said the Earth was the center of the universe was Claudius Ptolemy. Ptolemy was a Greek astronomer, mathematician, and geographer who lived in Alexandria, Egypt, during the 2nd century AD. He is best known for his geocentric model of the universe, which placed the Earth at the center of the universe, with the Sun, Moon, and stars orbiting around it. Ptolemy's model of the universe was widely accepted for over 1,400 years, until it was replaced by the heliocentric model of the universe, which placed the Sun at the center of the universe, with the Earth and other planets orbiting around it.