Scholar
Eratosthenes
Scholar and head of the Library of Alexandria
c. 276 – 194 BCE
Approximate dates.
Biography
A scholar from Cyrene who worked in Alexandria and headed its Library. He is credited with measuring the Earth’s circumference by comparing the sun’s shadow at Aswan and Alexandria.
Key facts
Certainty: Probable
Eratosthenes estimated the Earth’s circumference at about 250,000 stadia by comparing the sun’s shadow at Aswan and Alexandria.
Scholarly note: How accurate the result was is unresolved, because we do not know which length of stadion he used.
- Cleomedes (2004) “Cleomedes’ Lectures on Astronomy (trans. Alan C. Bowen and Robert B. Todd)” University of California Press, I.7
- P. M. Fraser (1972) “Ptolemaic Alexandria” Clarendon Press