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A Community Devoted to the Preservation and Practice of Celestial Navigation and Other Methods of Traditional Wayfinding
Re: Sun sights during an eclipse: "bad limb" calculation
From: David Pike
Date: 2023 Oct 17, 12:43 -0700
From: David Pike
Date: 2023 Oct 17, 12:43 -0700
Turning to part two of the 36” cord extension. If you nipped the extended cord close to the Earth’s surface all the way round until you reached the same point, then you would have 36” of cord left over from which you could make an 18” high loop. Therefore, the answer lies somewhere between 6” and 18”. If you said 12”, you wouldn’t be more than 6” out. That’s probably close enough for Government work. However, you could improve your estimate by considering the attached diagram.
rtanΘ – rΘ = 18” so if all else fails try for different values of Θ until LHS = RHS
Then knowing Θ, use cosΘ = r/(r+h) , or h = r/cosΘ – r to find h. As I’ve reached my maths limit, it would have to be via trial and error spreadsheet. DaveP
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