Biography of Aristarchus of Samos | Greek astronomer.

(Samos, Greece current, 310 BC - Alexandria, Egypt today, 230 BC) Greek astronomer. He spent most of his life in Alexandria. The scientific work of Aristarchus of Samos only has been preserved of the magnitude and the distance of the Sun and the Moon. He calculated that the Earth is some 18 times more distant from the Sun than the Moon, and the Sun was about 300 times larger than the Earth. The method used by Aristarchus was correct, but not measurements that established, because the Sun is about 400 times further. A pretty precise calculation was performed some decades later by Eratosthenes.

Aristarchus of Samos (Domenico Fetti oil)

Aristarchus of Samos made, also for the first time, a comprehensive heliocentric theory: while the Sun and the other stars are fixed in space, Earth and other planets revolve in circular orbits around the Sun. His heliocentric model (which had no followers in his era, dominated by the geocentric conception) found greater accuracy and detail in the Copernican system, already in the year 1500.

Aristarchus perfected in addition the theory of the rotation of the Earth on its own axis, explained the cycle of the seasons and made new and more accurate measurements of the tropical year.

Extracted from the website: Biografías y Vidas