Curvature Dilemma

A ship disappearing from the bottom first is an effect of Earth’s curvature. It is not a direct observation of the curve itself. We can only directly see the curve from a high altitude, not from near the surface.

Flat-Earthers present this reality as if it is a dilemma: 1. Earth is too big for us to see the curvature, but 2. We can see ships go over the curvature. It is a false dilemma. Ships disappearing from the bottom first is an effect of Earth’s curvature. Such an observation is different from directly witnessing the curve itself.

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Observation of Chicago From Michigan

Chicago’s skyline is visible on clear weather across Lake Michigan from Michigan as long as the observer is on high ground, or if atmospheric refraction is strong enough. This observation is consistent with the expectations if Earth is a sphere.

Flat-Earthers claim that the visibility of Chicago from Michigan is not possible if Earth is a sphere. In reality, they failed to account for the height of the observer or atmospheric refraction and ignored the fact that only the upper parts of the buildings are visible.

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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 of the Himalayas from India Due to COVID-19 Lockdowns

The lockdown due to the COVID-19 pandemic reduces air pollution in India. As a result, the Himalayas have become visible from 200 km (125 miles) away, consistent with the expectation if the Earth is a sphere 6371 km (3959 miles) in radius.

Flat-Earthers assert that the visibility of the Himalayas cannot possibly occur if Earth is a sphere as the distance is too far away. In reality, while the range is very far, the peaks are also very high, reaching more than 4400 m above sea level.

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Marine Radar

Marine radars can only detect objects above the horizon. The curvature of the Earth limits their detection range.

Some marine radars are marketed using their maximum ranges, which far exceed the typical over-the-horizon distances to another vessel. Flat-Earthers noticed the fact and used it as “evidence” against Earth’s curvature. In reality, the specified ranges are radar signal ranges. Earth’s curvature still limits the actual detection range.

While a marine radar with an advertised range of 50 nm will not detect vessels at that range, it is still useful and can identify higher-ground inland areas.

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Earth’s Curvature and the Size of a Coronavirus SARS-CoV-2 Causing the COVID-19 Outbreak

The surface of the water in a container with a width of one meter (3 ft) will have a curvature of 0.000002 cm from Earth’s gravity. As a comparison, a single SARS-CoV-2 coronavirus is at least 0.000005 cm in diameter, or at least 2½ times larger.

If a SARS-CoV-2 coronavirus is not visible to the naked eye, then there is no reason to expect that we will be able to see the much smaller curvature of the surface of water.

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Dizzib’s Earth Curve Calculator

Dizzib’s Earth Curve Calculator is one of the most popular Earth’s curvature calculator on the Internet. However, it does not account for atmospheric refraction and, therefore, unsuitable for determining the visibility of a distant object.

Many flat-Earthers used Dizzib’s calculator to analyze the observation of the visibility of a distant object and led them to an erroneous conclusion. If we can spot the calculator being used in their images, we can easily rule out their conclusion.

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Spirit Level on an Airplane

During cruising, an airplane is practically level. It is flying perpendicular to the direction of gravity. The aircraft is still flying following Earth’s curvature and continuously changes its orientation. However, not only its orientation changing but also the direction of gravity, having the same amount of change. As a result, a spirit level on a flight will not show us the difference in orientation of the airplane due to its motion following the curvature of the Earth.

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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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Toronto

The skyline of Toronto, Canada, is visible from across Lake Ontario, including from the cities of Hamilton and Niagara-on-the-Lake, as well as the Fort Niagara National Park. However, only its upper part is clearly visible, consistent with the spherical Earth model.

The upper parts of the skyline are affected less by atmospheric refraction, and more clearly visible. And the nearer to the horizon, the higher is the effect of atmospheric refraction. There are a few brighter colored buildings that appear above where they should be. These are the phenomenon of looming if they look upright, or superior mirage if they are upside down.

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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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Radio Propagation

Radio propagation is the behavior of radio waves as they travel from one point to another. As a form of electromagnetic radiation, radio waves are affected by reflection, refraction, diffraction, absorption, polarization, and scattering.

Flat-Earthers assume all radio waves are identical. They invented various “explanations” with the erroneous assumption. In reality, radio waves with different frequencies have different properties and different ways of propagation.

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The Legendary AutoCAD Diagram Involving the Pythagorean Theorem from Flat-Earthers

There is a legendary diagram of spherical Earth from flat-Earthers that was made using AutoCAD involving the Pythagorean theorem, flaunting the fact that it is was created “using AutoCAD 2016 with 15-digit precision”™. The diagram is not wrong, but it does not account for the height of the observer and atmospheric refraction. And therefore, it is unsuitable for determining the obstruction of a distant object due to Earth’s curvature.

The numbers in the diagram will give us a much higher number than it should be. If a distant object is visible, but according to the diagram it should not, then flat-Earthers will incorrectly conclude that the Earth is flat.

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The Angle of a Distant Object Due to Earth’s Curvature

Due to Earth’s curvature, a distant but still visible object is slightly leaning away from an observer. However, the angle is minuscule and undetectable to any observer.

After being shown photos showing the obstruction of a distant object due to Earth’s curvature, flat Earthers would often shift the topic by pointing out that the tilt due to Earth’s curvature is not apparent in those photos. In reality, the tilt is too small and not visible to our eyes.

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Offshore Wind Farms and the Curvature of the Earth

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Offshore wind farms consist of a series of large turbines having a similar shape and size. In some cases, they are spread over a very large area of water. They are suitable landmarks where we can easily observe the effect of the curvature of the Earth.

If the turbines are far enough, the bottom parts will not be visible and the blades can look as if they are submerged. The phenomenon is only possible if Earth is a sphere.

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Misleading “Debunking” of the Lake Pontchartrain Power Lines Images

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The various images of the Lake Pontchartrain power lines taken by Soundly and others easily demonstrate the curvature of the Earth. In a desperate attempt to “debunk” the images, a group of flat-Earthers made an “analysis”, but failed to locate the correct power lines. They incorrectly “analyzed” another power lines on the same lake, just not the ones being presented as a demonstration of Earth’s curvature.

The erroneous “analysis” spread in flat-Earth communities as a hoax, as though it “debunks” the actual power lines in the demonstration.

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Line of Sight: Determining if an Object is Straight or Flat

Light travels in a practically straight line over a short distance. We often use this property of light to determine if an object is flat or straight from visual observation.

Some flat-Earthers start with the wrong assumption that a specific object is flat, then attempt to redefine how our vision works from that. They are wrong. From visual observation, we can determine if an object is flat, not the other way around.

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Lighthouses and the Loom of the Light

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.

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