procedure, if I have constructed it correctly, is very remarkable... What is astonishing is the sophistication of approaching the problem by two quite different methods, and also the complete honesty with which Hipparchus reveals his discrepant results... which are nevertheless of the same order of magnitude and (for the first time in the history of astronomy) in the right region. See also Aristarchus of Samos (), a Greek mathematician who calculated the distance from the Earth to the Sun. Axial precession Eratosthenes (), a Greek mathematician who calculated the circumference of the Earth and also the distance from the Earth to the Sun. Greek mathematics Hipparchus () Posidonius (), a Greek astronomer and mathematician who calculated the circumference of the Earth. References F Hultsch, "...," Leipzig, Phil.-hist. Kl. 52 (1900), 169–200. N. M. Swerdlow, "Hipparchus on the distance of the sun," Centaurus 14 (1969), 287–305. G. J. Toomer, "Hipparchus on the distances of the sun and moon," Archive for History of Exact Sciences 14 (1974), 126–142. Hon, Giora. "Is there a concept of experimental error in Greek astronomy?." The British Journal for the History of Science 22.02 (1989): 129–150. (Available online at https://www.researchgate.net/profile/Giora_Hon/publication/231844424_Is_There_a_Concept_of_Experimental_Error_in_Greek_Astronomy/links/564fa57b08ae4988a7a858bd.pdf) Ancient Greek astronomical works Ancient Greek mathematical works Astronomy books