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How did Eratosthenes calculate the tilt of the Earth?

  1. Sep 6, 2012 #1
    Eratosthenes was a Greek mathematician who calculated the circumference of the Earth in 240 BC by using shadows and geometry. That's already ridiculous, but then I read he also calculated the tilt of the Earth! How did he do that?

    This guy was definitely a time traveller from the future. lol.
     
  2. jcsd
  3. Sep 6, 2012 #2

    Nugatory

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    Staff: Mentor

    I'm sorry, I may have misunderstood the question you're asking. I had thought that you were asking how to calculate the tilt of the earth from measurements that could be made with technology available in 240 BC..... In which case the answer is of course that it's half the difference between the height of the sun at high noon on the longest day of the year and the shortest day of the year (and of course there are a half dozen or so explanations of why in the first page of google results).

    I just found it amusing that this thread had made it onto that first page in less than twenty minutes after you started it. Apparently the google page ranking algorithm takes physicsforums.com very very seriously.
     
    Last edited by a moderator: Sep 7, 2012
  4. Sep 7, 2012 #3
    "this thread had made it onto that first page in less than twenty minutes after you started it. Apparently the google page ranking algorithm takes physicsforums.com very very seriously."

    This really is pretty remarkable, I just did a Google search and it came up on my first page too at only a few hours old; bots (spiders or whatever Google calls the program these days) are working overtime.

    You guys should try this, ha ha!
     
    Last edited: Sep 7, 2012
  5. Sep 7, 2012 #4

    Ryan_m_b

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    Staff: Mentor

    Keep it civil people
     
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