, we can perform the Eratosthenes experiment at many latitudes, one of which has the Sun directly overhead. If we do this, we can choose angles where Flat-Earth theory predicts shadows that increase in linear fashion with each angle. However, with the spherical-Earth measurement, the shadows will not increase linearly. In fact, if you perform the Eratosthenes measurement with two post, one of which is directly under the Sun, the calculated distance to the Sun in the flat-Earth picture differs for each distance to the second post. This explains why various Flat-Earth groups calculate different distances for the Sun.
Note that if one of the posts is placed near the North Pole, the resulting shadow for a spherical Earth will be extremely long. This is difficult to reproduce in the flat-Earth picture. This is one of the reasons Flat-Earthers are unable to state the exact distance from Earth to Sun; it varies according to the way they calculate this distance. Flat-Earthers “explain” the difference between the shadow measurements for spherical and flat Earth pictures as due to “refraction” of light (Flat-Earthers invoke “refraction” for many phenomena that cause them trouble). But they do not seem to have a consistent understanding of that term, or methods for accurately calculating refractive effects. In this case, Flat-Earthers argue that the Sun’s rays do not pass in a straight line to the Earth, but they travel in a curved path that allows them to obtain the same results as Eratosthenes.
Finally, consider the size of the Sun. Remember that the Flat-Earth Sun has a diameter of only 32 miles (this is obtained by noting that as viewed from Earth, the Sun subtends an angle of 0.5 degrees). If the Sun was only 3,000 miles away, then one can calculate that its diameter would be about 30 miles. We get a good idea of the relative size of the Sun by observing a transit of the planet Mercury. This occurs when the orbit of Mercury takes it directly between the Earth and the Sun. We then see Mercury moving across the Sun. Fig. II.18 shows a photograph of Mercury (the tiny black dot) passing across the Sun’s surface.
Reputable astronomers have measured Mercury’s diameter as about 3,000 miles. Note that Mercury appears as an infinitesimal dot in front of the Sun, with the line showing the motion of Mercury. This demonstrates that the Flat-Earth diameter of the Sun as 32 miles is completely wrong. And how does Mercury get between the Sun and Earth, anyway? In the Flat-Earth picture the Sun is 3,000 miles away from the Earth and Mercury should be on the celestial sphere, a hemispherical dome 4,000 miles above flat Earth.
We have included only a small number of the many serious issues with Flat-Earth Theory. Anyone interested in a comprehensive debunking of Flat-Earth theory should peruse the extensive discussions posted on Debunking Flat Earth Misconceptions. That should convince any objective observer that Flat-Earth Theory is full of holes and not worth serious consideration – it’s “flat wrong” 😊.