Eratosthenes
~276–194 BCE · Greek (Cyrene/Alexandria) · Hellenistic Period
Known for: First to calculate Earth's circumference with remarkable accuracy using shadows
Eratosthenes calculated the circumference of the Earth by comparing shadow angles in Alexandria and Syene—arriving within 2% of the correct value. He was chief librarian at Alexandria and a polymath—mathematician, geographer, astronomer, and poet.
He was nicknamed 'Beta' because he was second-best at everything—but second-best across every field.
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