One of the first known astronomers that supported the Heliocentric theory was Aristarchus of Samos. After observing a lunar eclipse, he came to the conclusion that the Sun was farther away from Earth than the Moon and that the Sun was much larger than Earth. He also claimed the Sun was a star. While Aristarchus was later an influence on Copernicus and his groundbreaking work, prior to the 17th century Aristarchus' findings were obstructed by the more established theories of Ptolemy and Aristotle.