An object is visible if it is either reflecting light or a light source itself. Furthermore, a reflecting object can have specular reflection (glossy finish, mirror-like), diffuse reflection (matte), or the combination of both.
Some flat-Earthers like to compare the appearance of the Moon to a glossy, metallic ball. Then, the difference in how the two objects look is taken as “proof” that the Moon is not reflecting light. They are wrong. A shiny metallic ball reflects almost all incoming light in mirror-like fashion, or that it has predominantly specular reflection. On the other hand, the Moon reflects incoming light to every direction, or that it has only the diffuse reflection.
Continue reading “Specular Reflection and Diffuse Reflection”
In photography, bokeh is the way a camera lens renders out-of-focus points of lights. The shape of bokeh depends on the camera lens more than the out-of-focus objects themselves.
Some flat-Earthers do not know how to take correctly focused pictures of distant planets and stars due to their lack of knowledge and the unsuitability of their camera for the purpose. All they are getting are bokeh, which does not tell us much about the intended objects.
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Earth’s atmosphere glows in blue because of Rayleigh scattering. It scatters sunlight to every direction. Bluish colors are scattered more than reddish colors. This results in the bright blue color of the sky in the daytime.
There are many misconceptions in the flat Earth community that arise from the lack of understanding of Rayleigh scattering.
Continue reading “Rayleigh Scattering”
Sun glitter is a bright, sparkling light formed when sunlight reflects from water waves. A rippled by a locally smooth surface such as water with waves will reflect the sun at different angles at each point on the surface of the waves. As a result, a viewer in the right position will see many small images of the sun, formed by portions of waves that are oriented correctly to reflect the sun’s light to the viewer.
Flat-Earthers take the long shape of the reflection of a sunset on an ocean surface as ‘proof’ that Earth is flat. They are wrong. Sun glitter is the result of rippling water. The difference in curvature between the flat and spherical Earth model is not that far to cause the difference in the shape of sun glitter.
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In most situations, atmospheric refraction bends light downwards and causes objects to appear higher than they actually are. The strength of atmospheric refraction is not constant. It depends on weather condition and varies on the different seasons, different days, and even different times of the day.
Because of the variability of atmospheric refraction, a distant object that is usually obstructed by Earth’s curvature can sometimes be visible. Some flat-Earthers would cherry-pick moments when the object is visible. They would show such specific moments to everyone and use them to “disprove” Earth’s curvature; happily ignoring the cases where Earth’s curvature partly or entirely obstructs the object.
Continue reading “Variability of Atmospheric Refraction”
On Earth, daylight sky is glowing in bright blue due to Rayleigh scattering. Sunlight is scattered in every direction by the oxygen and nitrogen molecules in Earth’s atmosphere.
Such the phenomenon does not happen on the Moon, causing the dark sky of the Moon. Flat-Earthers claim that the dark sky of the Moon captured by photos and videos taken from the Moon are “proof” there is misconduct. They are wrong. Just because Earth’s sky is bright blue, it does not mean it will be like that on the Moon and other planets.
Continue reading “The Dark Sky on the Lunar Daytime”
When we are unable to see a distant object, then it is due to one of these reasons:
- Our eyes lack the sufficient angular resolution to recognize the object.
- Atmospheric condition limits visibility.
- The object is far enough and obscured by Earth’s curvature.
Some flat-Earthers like to show that a previously unseen distant object can be brought into view using infrared vision. They would take that as ‘evidence’ of the non-existence of Earth’s curvature. They are wrong. Infrared vision can reveal hidden objects caused by visibility limitations, but not ones obscured by Earth’s curvature.
Continue reading “Infrared Vision”
Sunglint is a phenomenon that occurs when sunlight reflects off the surface of a water body —like the ocean— at the same angle as an observer is viewing the surface. In the affected area, relatively smooth ocean water becomes a silvery mirror.
In the flat-Earth model, the Sun is assumed to be a ‘local light source.’ They like to use a spotlight or a flashlight as an analogy. They present the sunglint phenomenon as ‘evidence’ of the fact that sunlight is local. They are wrong.
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Earth’s atmosphere scatters sunlight in every direction. Bluish colors are scattered stronger than reddish tones. As a result, the sky is glowing in bright blue during the day. The phenomenon is called the Rayleigh scattering.
Sometimes the Moon is visible during the day. The bright part of the Moon is bright because it is lit by the sunlight. On the other hand, its dark part does not receive sunlight, and thus barely emit any light. Because of these reasons, the dark part of the Moon is dominated by the blue color of the sky.
Continue reading “The Moon in Daytime and the ‘Transparent Moon’ Misconception”
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.
Continue reading “Fraunhofer Lines”
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.
Continue reading “Shadow on Clouds”
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.
Continue reading “Atmospheric Refraction and the Position of the Sun in the Flat-Earth Model”
The Sun has the angular size of approximately 0.53° seen from Earth, and it is practically constant throughout a single day. But sunlight is very intense and result in a glare that surrounds the Sun. Because of the intensity, we are unable to distinguish the Sun from its glare.
During a sunset, the intensity of sunlight is lower due to the fact that sunlight has to traverse Earth’s atmosphere at an angle. Because of the reduced intensity, the amount of glare will also be reduced, and the Sun can look as if it is shrinking.
Flat-Earthers often use this phenomenon as ‘evidence’ of a receding Sun during a sunset. They are wrong.
Continue reading “Sun Glare Makes the Sun Appear Larger”
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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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.
Continue reading “The Illusion of Clouds Appearing ‘Behind’ the Sun or the Moon”
During a total solar eclipse, the Moon is right between the Earth and the Sun. Thus, the near side of the Moon does not receive any sunlight. But while it is dark, it still gets some light reflected by the surface of the Earth. This phenomenon is called Earthshine.
Some flat-Earthers argue that a solar eclipse is not caused by the blocking of the Sun by the Moon, but by another, mysterious celestial body. The reason is that eclipses are incompatible with their beliefs about the motion of the Sun and the Moon.
Earthshine proves that they are wrong.
Continue reading “Earthshine Proves the Moon Obscures the Sun During a Total Solar Eclipse”
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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“The Sun and the Moon have been observed to appear in the sky at the same time during a total lunar eclipse. This cannot happen if the Earth is round because the Sun, Earth and Moon are supposed to be in a straight line during a total lunar eclipse. So, the globe Earth model is wrong!”
Some flat-Earthers observed the Sun and Moon appear at the same time during a total lunar eclipse. Predictably enough, they pick the most far-fetched explanation, and conclude the Earth is not round. But in reality, this phenomenon is well documented and clearly explained.
Continue reading “Selenelion: The Phenomenon Where The Sun and Moon Are Visible During a Total Lunar Eclipse”
The Moon turns red during a total lunar eclipse. But if the Moon is completely in Earth’s shadow, then how does it turn red?
The atmosphere of the Earth acts like a giant lens and refracts some of the sunlight into the surface of the Moon.
Continue reading “Blood Moon: Why The Moon Turns Red During a Total Lunar Eclipse”