Earthshine and Moon Phase

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.

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Interlaced Video and Deinterlacing

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Interlaced video is a technique for doubling the perceived frame rate of a video display without consuming extra bandwidth, especially with older display technology. With an interlaced video, a video frame is rendered twice, one after another, first for the odd-numbered lines and then for the even-numbered lines.

Flat-Earthers discovered objects appearing transparent in some footage from the ISS and use the fact as “evidence” the footage was faked. In reality, some of these artifacts are due to interlacing and the process of deinterlacing interlaced videos.

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Zooming at the Moon

At the longest zoom, the Nikon P1000 has a field of view of 0.2°, which is equivalent to 1342 km at the Moon’s distance.

Flat-Earthers zoomed their Nikon P1000 at the Moon and claimed that they could not find flags and landers from the Apollo missions. In reality, the smallest objects on the lunar surface they can observe using their cameras are large city-sized objects.

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Sun Glare

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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.

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Objects Obscured by Earth’s Curvature and Zoom Factor

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From an observer on a shore, the distance to the horizon is 5 km (3 miles), or more if the observer is higher. Therefore, Earth’s curvature obscures objects starting from that distance. If the objects are not large enough, we need an optical aid, like zooming in using a camera, to see them in the first place.

Flat-Earthers often show us wide-angle photos to demonstrate that objects are not obscured by Earth’s curvature. In reality, in such photos, objects far enough to be obscured by Earth’s curvature cannot be resolved. It is hard to see objects obscured by Earth’s curvature if the objects themselves are not visible in the picture.

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Coin on a Table “Experiment”

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Flat-Earthers performed the coin on a table “experiment” to “explain” how a sunset can occur on a flat Earth. Instead, it tells us more about their confirmation bias.

This is probably one of the most ridiculous flat-Earth arguments. It is so obviously wrong that many of us are having trouble explaining it and cannot accept that a member of the human race can fall for it.

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Earth Seen From the Moon vs the Moon Seen From Earth

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Earth seen from the Moon will appear 3.7× larger than the Moon seen from Earth. However, if a photograph of Earth is compared to that of the Moon, the sizes of both objects also depend on the field of view of the cameras that were used to capture them.

Flat-Earthers discovered the size of the Earth in a photograph is not 3.7× the Moon in another picture. They used the fact as “evidence” of wrongdoing. In reality, the two photos were not taken with the same field of view, and cannot be compared directly.

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South Star

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The pole star Polaris is used to locate the position of the north celestial pole because it is a bright star that is conveniently located very close to it. However, there is no corresponding bright South Star near the south celestial pole. To locate the south celestial pole, we need to observe stars around it.

There is no South Star as useful as Polaris in the north. Flat-Earthers use it to “disprove” the existence of the south celestial pole, which cannot possibly exist if Earth were flat. In reality, the south celestial pole can be easily shown and located. There is simply no bright star near it.

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Angular Resolution

Angular resolution is the minimum separation between distinguishable features in an image. Objects smaller than the angular resolution are indiscernible in the picture. The theoretical maximum angular resolution is determined by the diameter of the aperture of the optical instrument.

Flat-Earthers like to demand images of the lunar landers taken with a telescope as proof that the Apollo Moon landings did occur. In reality, no optical telescope on Earth is large enough to resolve the landers.

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Oblate Spheroid Shape of the Earth

The Earth is an oblate spheroid. Its diameter is longer across the equator than between the poles. The difference is tiny, only about 0.3%. It is not possible to notice the oblateness from photographs taken from space without careful measurement.

Flat-Earthers claim that in photos taken from space, Earth appears as a perfect sphere, unlike what science tells us, and they use it to discredit science. In reality, it is possible to notice the oblate shape with careful measurement of the images.

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Video Glitches

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In digital video, a missing or corrupted signal may result in glitches in the video. It can be caused by things like signal interference, scratches on Bluray discs, bad weather with satellite TV, damaged cables, Internet link congestion, etc.

Flat-Earthers like to scrutinize videos taken from space. If they find the glitches, they will swiftly use them as “evidence” of manipulation. In reality, such glitches in the videos are not unusual. We can easily encounter them on other occasions.

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Camera Entrance Pupil Size and the Zoom Factor

The entrance pupil is the opening in front of a camera that allows light to enter. If it is partially obscured, light can still come through the unobscured part, and the camera can still see the object.

In one of those “experiments,” flat-Earthers placed an obstacle in front of a camera, very close to the lens, so that an object is partially visible. At the widest angle setting, the person appears partially visible. But it turned out that zooming in will fully reveal the person. Flat-Earthers claim it is how objects can vanish behind the horizon if Earth is flat and how they can reappear by zooming in. In reality, zooming enlarges the camera’s entrance pupil, letting the camera to see over the obstacle.

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Visibility Range vs Angular Resolution

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.

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Andromeda Galaxy

The Andromeda Galaxy is the nearest major galaxy. It is visible to the naked eye on dark nights and the easiest deep-sky object to capture even without special equipment.

There are many images of Andromeda on the Internet because it is not that hard to capture it. Flat-Earthers assumed the pictures are the Milky Way and immediately claimed those pictures as fakes. In reality, the galaxy in the photographs is the Andromeda, and it is not hard for anyone to take a picture of it. The “you are here” sign on some pictures of the Andromeda Galaxy is silly and an obvious spoof. It was merely an attempt on a joke.

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Observing Geostationary Satellites

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Geostationary satellites orbit the Earth with the same rate as Earth’s rotation, 35786 km (22236 miles) above the equator. They are too far and too dim for the naked eye. However, we can observe them using a mounted telescope and a camera.

We can observe many of them by:

  • using an equatorial mount,
  • aiming the telescope at a star that lies in the orbit’s path, and
  • use a camera with a long exposure setting.

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Telephoto Lenses and the Appearance of Earth’s Curvature

A telephoto lens is a type of lens in which the physical length is shorter than the focal length. A telephoto lens has a narrow field of view, and as a result, the curvature of the Earth is less pronounced if taken using a telephoto lens compared to another lens with a wider field of view.

Flat-Earthers like to bring up pictures taken from the ISS that show a practically flat horizon, and use them as evidence of inconsistency. In reality, the images were taken using a telephoto lens with a narrow field of view.

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Zooming in on a Partially Obscured Ship

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Zooming in makes the camera’s field of view narrower, and in effect, it magnifies the center portion of the image. Zooming in using the optical zoom can improve angular resolution, but will never reveal a distant object that is obscured by another object.

Flat-Earthers claim that zooming in will fully reveal a ship that is partially obscured. In reality, the proportion of the ship which is hidden compared to that which is visible stays the same in the entire zoom range.

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Infinity Focus

To an optical device, like a camera, there is little difference between an airplane at 20000 ft and the Moon at 384400 km (238855 mi). The aperture of the lens is far too small compared to the distance of either object. Focusing on either object will make the other object in focus, too.

Flat-Earthers claim that because both objects appear in focus in a photograph, then the Moon must be close to the airplane. In reality, both can be considered at infinity. And it will be easy to make both objects to be in focus simultaneously.

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Magnifying Images Vertically to Reveal Earth’s Curvature

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The horizon appears flat because the curvature is too small when observed from near the Earth’s surface. However, in some cases, we can exaggerate the curve by taking photographs of the horizon and then magnifying the results vertically.

Magnifying in such a way will also magnify the distortions introduced by the camera lens. We will need to control these distortions using proper photography techniques, or by placing a known straight object as a control object in the frame, close to the horizon. If successful, then the remaining curvature in the photograph can only come from the curvature of the Earth.

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Visualization of Satellites and Space Debris

Various pictures showing satellites and space debris around the Earth are visualizations. They are not real photos taken from cameras. These visualizations were created by drawing the objects with sizes far larger than their actual dimensions. If they were drawn to scale, then they all will be too small and cannot be seen in the visualizations.

Flat-Earthers fail to realize that these are visualizations. They think the pictures are presented as real photos. Because we never see satellites like that, they concluded that it was a deception. In reality, these pictures are simply visualization, not actual photos.

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