Can You Detect the Earth's Curvature from a Lighthouse?

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Discussion Overview

The discussion revolves around the possibility of detecting the Earth's curvature from a lighthouse using precise instruments. Participants explore theoretical and practical aspects of this detection, including the influence of atmospheric conditions and observational techniques.

Discussion Character

  • Exploratory
  • Technical explanation
  • Debate/contested

Main Points Raised

  • Some participants suggest that measuring the angle between the horizon and the horizontal could theoretically allow for detection of curvature, but practical challenges exist.
  • There are anecdotes about lighthouse keepers observing ships and their masts as they approach, which some argue confirms the curvature of the ocean surface.
  • Others assert that no flat earther has successfully measured the curvature, implying that the task is straightforward under the right conditions.
  • Concerns are raised about atmospheric refraction affecting precision and the dip of the horizon, which may complicate detection efforts.
  • A distinction is made between "detecting" and "measuring" curvature, with some noting that detection could be problematic in certain conditions, such as with Fata Morgana mirages.

Areas of Agreement / Disagreement

Participants express differing views on the feasibility of detecting the Earth's curvature from a lighthouse, with some asserting it is theoretically simple while others highlight practical difficulties. No consensus is reached regarding the effectiveness of various methods or the implications of atmospheric conditions.

Contextual Notes

Limitations include the potential impact of atmospheric refraction and the variability in horizon dip, which may affect detection outcomes. The discussion does not resolve these complexities.

zuz
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If you stood on a lighthouse high above with a very accurate transit, would you be able to detect the curvature of the earth?
 
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You mean, by measuring the angle between the horizon and (ironically) the horizontal? Yes, in principle. To see if it's possible in practice depends on looking up the precision and accuracy of your instrument and a fairly straightforward exercise in trigonometry.
 
There is an old tale that lighthouse keepers with telescopes would watch for expected sailing ships then warn merchants below with appropriate flags for different vessels. First they saw the tips of the tallest masts on the horizon, then the sails, then the body of the approaching ship; thereby confirming the curvature of the ocean surface.
 
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Klystron said:
There is an old tale that lighthouse keepers with telescopes would watch for expected sailing ships then warn merchants below with appropriate flags for different vessels. First they saw the tips of the tallest masts on the horizon, then the sails, then the body of the approaching ship; thereby confirming the curvature of the ocean surface.
Or from the other direction, it is a standard thing in ship navigation to have handy a table of height vs horizon distance in order to predict when (how far away) you should see navigation aids.
 
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No flat earther has ever been able to measure the curvature of the earth.
 
profbuxton said:
No flat earther has ever been able to measure the curvature of the earth.
I doubt one can be a flat earther put an honest effort into it. It really isn't hard. The method described here requires only a nice day on the beach with a pair of binoculars, watching ships (with access to google and/or a ship tracking app).
 
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zuz said:
If you stood on a lighthouse high above with a very accurate transit, would you be able to detect the curvature of the earth?
Theoretically, it is easy. Practically not so.
Regarding precision one may face problems due to refractive index of atmosphere, and the change in the dip of horizon from case to case. Read old article considering these issues:
http://www.fer3.com/arc/imgx/Dip-of-the-horizon-Freiesleb.pdf
 
zoki85 said:
Theoretically, it is easy. Practically not so.
Regarding precision one may face problems due to refractive index of atmosphere, and the change in the dip of horizon from case to case. Read old article considering these issues:
http://www.fer3.com/arc/imgx/Dip-of-the-horizon-Freiesleb.pdf
"Detect", not "measure".

Note, atmospheric refraction at the horizon is partially a function of Earth's curvature too.
 
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russ_watters said:
"Detect", not "measure".
A mere detection can be issue in extreme cases. Fata Morgana mirages
 

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