On the Sizes and Distances of the Sun and Moon (Book) AKA Περὶ μεγεθῶν καὶ ἀποστημάτων [ἡλίου καὶ σελήνης]
On the Sizes and Distances of the Sun and Moon
240 BC
AKA Περὶ μεγεθῶν καὶ ἀποστημάτων [ἡλίου καὶ σελήνης]
In On the Sizes and Distances Aristarchus makes certain hypotheses based on common observations of the heavens and comes to the conclusion that the sun is at the center of the universe with the Earth rotating around it! His observations include the the apparent size of the sun and moon in the sky, the size of the Earth's shadow on the moon during an eclipse, and the idea that during a half moon the angle between the sun and the moon is 90°. He then calculates distances such as the distance from Earth to moon and sun, as well as the sizes of these bodies. Archimedes's describes it in detail in his own book The Sand Reckoner.
