What is the main reason of the discrepancy I found here?
6
175Ṁ178
Apr 17
12%
Misalignment between hilltops and horizon in the pictures
35%
Wrong identification of the hills
15%
Wrong distance or altitude of the hills or reference point
12%
Atmospheric refraction
5%
The Earth is not spherical
7%
Local geographical features
14%Other

Trying to measure the radius of the Earth with simple observations following Al Biruni’s method: https://mariopasquato.substack.com/p/its-easy-to-say-abu-rayhan-muhammad

It doesn’t work that much. Order of magnitude is right, but the number is off.

Resolves to my own assessment a month from now.

Get
Ṁ1,000
to start trading!
Sort by:

Is my understanding of the geometry correct? If so, I'm not sure your way of calculating the depression angle is correct, since I get a different answer. However, it doesn't change the numerical values much

@KnMatt I am assuming that the nearby hills are much closer to me than the horizon, so locally the Earth is flat. This should be right if the radius of the Earth is indeed ~1-10 thousand kilometers: the hills are a few km away and the horizon should be about 80km away. A bit of circular reasoning, could be avoided by doing the exact calculation.

That was pretty entertaining, thanks!

© Manifold Markets, Inc.•Terms + Mana-only Terms•Privacy•Rules