On the Sizes and Distances (Aristarchus)

On the Sizes and Distances (of the Sun and Moon) (Ancient Greek: Περὶ μεγεθῶν καὶ ἀποστημάτων [ἡλίου καὶ σελήνης], romanized: Perì megethôn kaì apostēmátōn [hēlíou kaì selḗnēs]) is widely accepted as the only extant work written by Aristarchus of Samos, an ancient Greek astronomer who lived circa 310–230 BCE. This work calculates the sizes of the Sun and Moon, as well as their distances from the Earth in terms of Earth's radius. The book was possibly preserved by students of Pappus of Alexandria's course in mathematics, although the evidence for this is sparse.

Source: Wikipedia — On the Sizes and Distances (Aristarchus) (CC BY-SA 4.0)