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Name: Elizabeth
Status: other
Grade: other
Location: NV
Country: N/A
Date: N/A

I am trying to find out who is historically credited with figuring out that the seasons are the result of earth's tilt. Was it Kepler? Newton? Galileo? Someone more recent? Can you provide a reference?

Dear Elizabeth,

Good question! The Greek philosopher Oenopides is credited to be the first to calculate Earth's tilt. He can up with a value of 24 degrees, around 480 BCE. Since the correct value was 23.5 degrees, he was pretty close. However, exactly what he meant by it may be uncertain. I think you are correct that the time of Kepler and Galileo is about the time that scientists understood that the Earth's tilt caused the seasons. As soon as the Copernican system was accepted, the Earth's tilt became far more important. I am sorry not to be able to put a single name on your question, but I suspect that Galileo had a lot to do with it.

David Levy

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