Given that ancient greeks knew the earth was round since around 500BC and Eratosthenes calculated (more or less precisely) the circumference of the earth around 200BC, why is it that Christopher Columbus thought he was in Asia when he landed?

by PinkPercival

If he knew the circumference of the earth, would he not have realised he hadn't traveled far enough to cross both the Atlantic and the Pacific? Also, did people just think there was a massive ocean the size of the Atlantic + the Pacific + the Americas?

jschooltiger

Columbus thought he had sailed around the globe to land in Indonesia; that wouldn't happen if the earth weren't round, and the voyage to Indonesia was the whole point of his travels. He both overestimated the size of Eurasia and underestimated the circumfrence of the Earth. I wrote about this here.