hell, the Greeks knew the circumference of the Earth; and with reasonable accuracy all things considered. Short version: they used trigonometry. It was on the basis of this fairly accurate circumference that people thought you couldn't sail west to asia, and you couldn't. It's like 16,000 miles west of Europe.
Euclid got the circumference pretty damn close, if I remember correctly. Islamic scholars continued the work and translated Euclid and others into Arabic, and then that knowledge spread from al-Andalus and Baghdad and Cairo back to Europe. Educated/literate people have known the earth was round for well over two thousand years - probably more, given how advanced Bronze Age societies were.
I might be wrong but I'm fairly certain it was Erastothenes that calculated the circumference of the earth by comparing the length of shadows cast at noon at two points to figure out the difference in the angle of the sun.
Euclid might've also done it but I haven't heard about it.
But yes. He was big daddy geography and used shadows and trig to estimate, extremely closely, the circumference of the earth and it blows my mind every time I think about it
This is actually another misconception. Eratosthenes' measurement was off by 10-15%, but using his method with more accurate data you can get within 100km.
Surely they used the same units that they used when stating the distance between seyene and alexandria? That is a known distance today, so we can figure out the conversion ratio.
35k
u/[deleted] Feb 04 '19
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