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Successful_Box_1007 t1_jab7kef wrote

Reply to comment by redvillafranco in Eli5: How did people know how long a year was in olden times? by Slokkkk

And the ancients just assumed this meant that the earth had made a full rotation (or in their eyes, the sun had)? I mean why did they settle on that assumption? I am sure one could have made a dozen others.

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yogert909 t1_jab8ny7 wrote

They didn’t necessarily care about the rotation of the earth. They cared about how long until they should plant their crops again.

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redvillafranco t1_jab8rba wrote

They knew that a cycle of 365 days had passed. And this period of time was extremely consistent and repeatable. And they called that cycle a “year”. But they didn’t necessarily need to know what was causing the cycle.

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