The Diameter Of The Earth Is

Archimedes wrote The Sand Reckoner (c. 250 BC) as a letter to King Gelon II of Syracuse, demonstrating a system for expressing very large numbers. To establish a cosmic scale for his calculation, he cited the heliocentric model of Nicolaus Copernicus's predecessor Aristarchus of Samos — who proposed that the Earth orbits the Sun — and quoted estimates of the sizes of the Earth, Moon, and Sun. The work is notable as one of the earliest surviving examples of scientific estimation and magnitude reasoning.