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

[zuz]

If you stood on a lighthouse high above with a very accurate transit, would you be able to detect the curvature of the earth?

 

[Ibix]

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.

 

[Klystron]

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.

 

[russ_watters]

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.

 

[profbuxton]

No flat earther has ever been able to measure the curvature of the earth.

 

[russ_watters]

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).

 

[zoki85]

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

 

[russ_watters]

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.

 

[zoki85]

"Detect", not "measure".

A mere detection can be issue in extreme cases. Fata Morgana mirages