How did Eratosthenes calculate the tilt of the Earth?

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    Earth Tilt
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Discussion Overview

The discussion revolves around how Eratosthenes calculated the tilt of the Earth, exploring historical methods and the context of his calculations. It touches on both the mathematical and observational techniques that could have been employed in ancient times.

Discussion Character

  • Exploratory, Conceptual clarification, Meta-discussion

Main Points Raised

  • One participant notes that Eratosthenes calculated the circumference of the Earth using shadows and geometry, expressing surprise at his ability to also calculate the tilt.
  • Another participant suggests that to calculate the tilt of the Earth with the technology available in 240 BC, one could measure the height of the sun at noon on the longest and shortest days of the year, indicating a method based on solar observations.
  • A later reply comments on the rapid visibility of the thread in Google search results, reflecting on the engagement and interest in the topic.
  • Another participant emphasizes the importance of maintaining civility in the discussion.

Areas of Agreement / Disagreement

Participants express varying degrees of understanding regarding Eratosthenes' methods, with some focusing on the historical context and others on the technical aspects. No consensus is reached on the specifics of how the tilt was calculated.

Contextual Notes

There are limitations in the discussion regarding the assumptions made about the methods available in 240 BC and the definitions of the measurements involved in calculating the tilt.

myshadow
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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.
 
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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.
 
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"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:
Keep it civil people
 

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