Eratosthenes and Flatland: a 55 km Sun at 6,333 km
A calculation applies trigonometry to the Eratosthenes experiment: if the Earth were flat, the Sun would be 6,333 km away and 55 km across. Eclipses…
English · Original discussion in Spanish · Published
If the Earth were flat, the Sun would be 55 km in diameter
Eratosthenes was not trying to prove that the Earth is spherical: that was already known in his time. In the 3rd century BC he measured shadows in Alexandria and Syene and obtained a finer figure, the radius of the planet. Flat Earth advocates use the same experiment to arrive at a result that exposes them. If the surface were flat, the Sun would have to be 6,333 km high and only 55 km in diameter.
The Sun that shrinks in Flatland
The reasoning is simple. With a 7.2-degree difference in the Sun's position between the two cities and a distance of about 800 km, trigonometry gives the height. On a sphere, that arc becomes curvature. On a plane, the Sun ends up at 6,333 km. And since its angular size is half a degree, the resulting diameter is 55 km. A miniature Sun for an imaginary world that has trouble with eclipses.
The eclipse problem
That is not the end of it. The Moon would sit at the same height and with the same diameter. Two twin bodies 6,333 km away make eclipses as we observe them impossible. It is the kind of detail that rarely appears on flat Earth maps.
The survey asked flat Earth defenders to do the calculation. Someone did, with the help of an AI. The result is a 55 km Sun and a twin Moon. It is not a matter of belief: it is a matter of arithmetic.
Eratosthenes was not trying to prove that the Earth is spherical: that was already known in his time. In the 3rd century BC he measured shadows in Alexandria and Syene and obtained a finer figure, the radius of the planet. Flat Earth advocates use the same experiment to arrive at a result that exposes them. If the surface were flat, the Sun would have to be 6,333 km high and only 55 km in diameter.
The Sun that shrinks in Flatland
The reasoning is simple. With a 7.2-degree difference in the Sun's position between the two cities and a distance of about 800 km, trigonometry gives the height. On a sphere, that arc becomes curvature. On a plane, the Sun ends up at 6,333 km. And since its angular size is half a degree, the resulting diameter is 55 km. A miniature Sun for an imaginary world that has trouble with eclipses.
The eclipse problem
That is not the end of it. The Moon would sit at the same height and with the same diameter. Two twin bodies 6,333 km away make eclipses as we observe them impossible. It is the kind of detail that rarely appears on flat Earth maps.
The survey asked flat Earth defenders to do the calculation. Someone did, with the help of an AI. The result is a 55 km Sun and a twin Moon. It is not a matter of belief: it is a matter of arithmetic.
Also available in: Deutsch
Summary of a discussion on Burbuja.info - Foro de economía, actualidad y política., translated from Spanish and reviewed before publication. Read the full discussion (28 replies).
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