Category: Optical Phenomena

Fraunhofer Lines

Sunlight can be broken into its constituent colors using a prism. The colors are the optical spectrum of the Sun. They are the same colors on rainbows. On careful observation, the spectrum is not perfectly continuous, but it has dark lines scattered over the entire spectrum. It turned out that from the lines, we can tell the composition of the Sun without physically getting there.

Some flat-Earthers think that it is impossible for us to determine the composition of the Sun, as it is impossible for anyone to visit the Sun without getting roasted in the process. They are wrong. The composition of the Sun can be determined from the spectral lines, or more specifically for the Sun: the Fraunhofer lines.

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Shadow on Clouds

Before sunrise or after sunset, the Sun is below the horizon and not directly visible. But the sky and clouds above are illuminated because they are high above, and sunlight can reach them.

If there’s a mountain between the Sun and the clouds, it can cast a shadow on the clouds. The flat-Earth model assumes the Sun is always high above, and thus, this phenomenon cannot possibly occur in a flat-Earth.

The fact that a mountain can cast its shadow on clouds far above it is evidence that the Earth is spherical.

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Atmospheric Refraction and the Position of the Sun in the Flat-Earth Model

If the Earth is flat, then the Sun would have been visible from the entire Earth, but that’s not the reality. So, to rescue the concept of the flat-Earth from being falsified, they invented an ad-hoc hypothesis that the Sun appears to set because of perspective and refraction.

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Atmospheric Refraction

Light waves are not always moving in a straight line. When it passes through a medium of a different refractive index, the waves will deviate. The phenomenon is called refraction and described according to Snell’s Law.

Earth’s atmosphere has variation in air density that depends on the altitude. As the refractive index changes with the density of the medium, light waves passing through Earth’s atmosphere also experience refraction.

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The Illusion of Clouds Appearing ‘Behind’ the Sun or the Moon

Sometimes, we can see clouds appearing as if they are behind the Sun or the Moon. Obviously, this is merely an illusion. But some flat-Earthers regard this as ‘evidence’ that the Sun and the Moon are close and apparently closer than some clouds. They are wrong.

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Crepuscular Rays

Some flat-Earthers consider crepuscular rays as evidence that the Sun is not far. In their mind, the Sun is only about ±5000 km circling above us. In reality, the actual distance of the Sun is ±150 million km.

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