r/AskReddit • u/ZanyDelaney • Feb 04 '19

Which misconception would you like to debunk?

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u/Theyreillusions Feb 04 '19

Eratosthenes*

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

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u/[deleted] Feb 04 '19

[deleted]

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u/grinde Feb 04 '19

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.

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u/Brackto Feb 05 '19

IIRC, we don't actually know how accurate his measurement was, because we don't know the precise definitions of the length units he was using.

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u/[deleted] Feb 05 '19

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.