The Moon becomes red during a total lunar eclipse because Earth’s atmosphere acts like a lens and refracts sunlight toward the Moon. It also scatters bluish components of sunlight more strongly and lets more reddish components reach the Moon.
The Moon does not become totally dark during a total lunar eclipse, and flat-Earthers use it as “evidence” the Moon is not in Earth’s shadow during a lunar eclipse. In reality, it occurs due to optical phenomena involving Earth’s atmosphere.
Continue reading “Blood Moon: Why The Moon Turns Red During a Total Lunar Eclipse”
Atmospheric refraction is stronger near the surface. Additionally, a thermal inversion can form a duct guiding light ray to follow the curvature of Earth. These phenomena allow light rays to reach the viewer far behind the horizon, but the rays will be compressed, distorted, and scattered, and will not form the true image of the objects. However, a nondescript, intense point light source will stand out against a darker background.
Flat-Earthers like to perform experiments involving lasers, flashlights, and mirrors over the water surface. If the light is visible from the other side, they would wrongly conclude Earth’s curvature does not exist. In reality, atmospheric refraction causes the result they observed.
Continue reading “Experiments Involving Flashlights, Laser, & Reflected Sunlight Over Water Surface”
We can see an object farther over Earth’s curvature if we and the object are higher. Mountain peaks are the highest points on Earth. As a result, from a mountain peak, it is possible to observe another peak very far away, even over hundreds of kilometers. The website Beyond Horizons discusses these records of observation.
Flat-Earthers use some of the world records of the farthest peak to peak observation as “proof” of flat Earth. In reality, these observations are possible because the peaks are very high, and atmospheric refraction helps the observation. These observations agree with the expectation if Earth is a sphere.
Continue reading “Beyond Horizons: World Records of Farthest Pictures Taken on Earth”
The Statue of Liberty was once used as a lighthouse. Its light can be seen from 24 miles away. Like other lighthouses, it can produce the loom of the light due to scattering in the atmosphere, which allows its light to be seen from much farther away.
Flat-Earthers use the visibility of the Statue of Liberty from 60 miles away as “evidence” of flat Earth. In reality, the effect of the loom of the light is what might be visible under clear weather, but the structure itself is not. Today, the Statue of Liberty is no longer used as a lighthouse, and nothing of it can be seen from that far away. But the information still spreads in flat-Earth communities as a hoax.
Continue reading “Statue of Liberty”
Earthshine is a glow in the dark areas of the Moon because sunlight reflects off Earth’s surface to the Moon’s night side. Earthshine can be easily observed with long-exposure photography.
Some flat-Earthers claim that the Moon is transparent or that it is not a sphere. By observing the earthshine using a camera with the correct exposure, we can easily disprove such claims.
Continue reading “Earthshine and Moon Phase”
Sunlight is very intense. It can cause glare to appear around the sun, and as a result, the sun can appear larger than its actual size. To observe the sun’s actual size, we need to eliminate the glare by reducing the camera’s exposure or using a solar filter.
During sunset, sunlight gradually becomes less intense, and sun glare gradually becomes smaller. If the glare is not eliminated, the sun can appear as if it is shrinking, and flat-Earthers incorrectly use it as “evidence” that the sun is moving away from us.
Continue reading “Sun Glare”
Refraction is the change in the direction of light due to the change in the medium’s refractive index traveled by the light. It is convenient to use water in a demonstration of refraction. But water alone is not the cause of refraction.
Flat-Earthers falsely claim that just because our atmosphere has water vapor in it, it will produce the same effect as any demonstration of refraction involving water. In reality, it requires far more reasoning than just that water is involved.
Continue reading “Refraction and Water”
A selenelion occurs during a lunar eclipse when the sun and moon are observed above the horizon. Atmospheric refraction bends light rays and lifts the image of the sun, and the moon typically up to 0.6°, so both can appear above the horizon.
Flat-Earthers assert that a selenelion should not be possible if Earth is a sphere due to the fact during a lunar eclipse, the sun and moon are 180° apart. In reality, a selenelion is possible because Earth’s atmosphere refracts light.
Continue reading “Selenelion: The Phenomenon Where Both the Sun and Moon Are Visible During a Total Lunar Eclipse”
Visibility range is a measure of the distance at which an object can be clearly discerned. Angular resolution is the ability of an optical system to resolve detail in the object.
Unlike the claim from flat-Earthers, there is no such thing as the “maximum range” of a camera. A germ on our hand is well within the visibility range, yet a regular camera lacks sufficient angular resolution to see it. On the other hand, an airplane is much farther away, but it has a larger angular size and can be seen by the camera.
Continue reading “Visibility Range vs Angular Resolution”
An inferior mirage is a phenomenon in which atmospheric refraction bends light rays to produce a mirrored image below a real object. It occurs when a hot surface heats the layer of air above it, placing it below a colder & denser layer of air.
Flat-Earthers like to use inferior mirages to “explain” how a distant object can appear partly obstructed if the Earth is flat. In reality, an inferior mirage cannot produce an appearance similar to an object partially obscured by Earth’s curvature.
Continue reading “Inferior Mirage”
Flat-Earthers use the phenomenon of refraction as a catch-all “explanation” every time they observe something not appearing in the expected position if the Earth is flat. They use the term “refraction” as mere technobabble without any underlying explanation.
The following are how we can distinguish real-world, scientific refraction from the technobabble used by flat-Earthers:
Continue reading “Refraction: Only a Baseless Technobabble in Flat Earth Community”
Earth’s shadow is the shadow that Earth casts into its atmosphere, toward the opposite point from the sun. Above Earth’s shadow is the Belt of Venus, a pink band from the scattering of sunlight through the atmosphere.
Earth’s shadow lies at the antisolar point —the point opposite the sun. It rises when the sun sets and sets when the sun rises. The phenomenon shows us that the sun really goes below the horizon and disproves the flat Earth model.
Continue reading “Earth’s Shadow and the Belt of Venus”
The distance to the horizon depends on the height of the observer and atmospheric refraction. The variability in atmospheric refraction can make the horizon appear in front of a distant object sometimes, and behind it in other times.
Some flat-Earthers raised a case —dubbed the “black swan” case— in which the horizon appears to be behind a distant object which is farther than the distance to the horizon according to calculation, and they use the fact to “disprove” Earth’s curvature. In reality, they did not account for atmospheric refraction, and that the amount of refraction varies.
Continue reading “Distance to the Horizon & the Black Swan Observation”
The appearance of sunset depends on atmospheric conditions. Thermal inversion can irregularly refract light coming from the sun and distort the image of the Sun seen from an observer.
Some flat-Earthers observed a specific appearance of sunset and presented the fact as if it “proves” a receding sun in the flat-Earth model. They are wrong. The appearances of the sunsets are the results of atmospheric refraction.
Continue reading “The Appearance of Sunset and Atmospheric Refraction”
Lighthouses are equipped with powerful lights. In a dark night, even if Earth’s curvature obscures the entire structure of the lighthouse, the phenomenon of the loom of the light allows their lights to be visible beyond the horizon; not unlike how the beam of a green laser is visible to our eyes.
Flat-Earthers like to point out the cases where the light from a lighthouse is visible even if the lighthouse should be completely obscured by Earth’s curvature. They would claim it as “proof” that the Earth is flat. They are wrong. The loom of the light lets us see the light even when the lighthouse itself is below the horizon.
Continue reading “Lighthouses and the Loom of the Light”
Flat-Earthers like to perform the experiment involving lasers to ‘disprove’ Earth’s curvature. If they observe a laser beam from the other side of a lake or an ocean, they would wrongly conclude Earth’s curve does not exist. It was merely a misunderstanding of how lasers work.
Continue reading “Flat-Earthers’ Laser Tests are Misleading”
Camera zoom works by enlarging the center portion of the image, or in other words, by making its field-of-view narrower. Zooming in on the setting sun will not reveal more of the sun, and will only enlarge the size of the sun in the resulting image.
Flat-Earthers are claiming that zooming in on a setting sun will reveal the entire sun, and somehow lift it out of the water. They are wrong. They simply used the incorrect exposure settings. In reality, zooming on the setting sun will never reveal the sun that is already obstructed by Earth’s curvature.
Continue reading “Zooming-In on the Setting Sun”
A sun dog is an atmospheric optical phenomenon that consists of a bright spot separated by 22° from the Sun to one or both sides of the Sun. It is caused by the refraction of sunlight by ice crystals in the atmosphere.
Flat-Earthers claim that a sun dog is caused by the reflection of sunlight by the mythical dome enclosing the flat Earth, that there are multiple suns, or other equally implausible reasons. They are wrong. A sun dog is simply an optical phenomenon that occurs in cold locations where ice crystals can accumulate in the atmosphere.
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Visual albedo is the measure of the reflection of solar radiation out of the total solar radiation received by an astronomical body, taking into account only the visible light. The visual albedo of the Earth is 0.37, and the Moon’s is 0.12.
The Moon appears darker if the Earth also appears in the same photograph. Flat Earthers use the fact to “prove” that the picture is fake. They are wrong. The Moon appears darker because it reflects less sunlight than the Earth.
Continue reading “Visual Albedo of the Moon and the Earth”
A solar filter is utilized to reduce the intensity of sunlight and enable a camera to capture the image of the sun with the correct exposure, even under bright daylight. Without a solar filter, sunlight can be too bright to be correctly exposed by a camera.
Some flat-Earthers made their observation of the sun using a camera without a solar filter. As a result, in some of their images, the sun appears much larger due to the fact the camera cannot distinguish the sun and the sun glare around it.
Continue reading “Solar Filter”