Visibility of Africa from Spain and Vice Versa

The Strait of Gibraltar separates the Iberian Peninsula and Africa. The two are separated only by 13 km (8.7 miles) at the narrowest point. We can easily see Africa from Spain as it is not that far away and that there are many highlands on both sides.

Flat-Earthers present the visibility of Africa from Spain as “evidence” Earth is flat. In reality, Africa is not that far from Spain. It is not far enough for the curvature of Earth to obstruct our view of Africa from Spain and vice versa.

Curvature App

Curvature App is a web application we can use to create a simulation of the horizon’s shape and the visibility of distant objects on a flat and spherical Earth. Curvature App is available at walter.bislins.ch/Curve.

When determining a distant object’s visibility, flat-Earthers often use wrong calculators that fail to account for all the important variables and give them incorrect results. Curvature App accounts for all of these variables, and not only it gives us the numbers, but also the simulated view.

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Beyond Horizons: World Records of Farthest Pictures Taken on Earth

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.

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Statue of Liberty

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.

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Bonneville Salt Flat and Earth’s Curvature

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Interstate 80 traverses the Bonneville Salt Flat, Utah, in a practically straight segment. From the hilly terrain to the west of the highway, we can observe the highway’s curve following Earth’s curvature using a long-zoom camera.

Flat-Earthers incorrectly claim that salt flats are perfectly flat and use them to “prove” a flat Earth. In reality, salt flats form a curve following Earth’s curvature, like the ocean’s surface.

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Exalt’s Mediterranean Microwave Transmission Link

One of the longest microwave links is between Lebanon and Cyprus, spanning 235 km (146 miles). To clear Earth’s curvature, both transceivers need to be placed on high ground. In the illustration, we provide an example where we can install both transceivers to establish the link.

Flat-Earthers claim that the link can only be established if Earth is flat. In reality, it is trivial to find locations in Lebanon and Cyprus where we can set up a microwave link between them that clears Earth’s curvature without using any towers and still leaves us with plenty of wiggle room.

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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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Magnetic Dip

A magnetic compass is less usable near the poles partly due to magnetic dip. One of the Earth’s poles is much closer and affects the needle more strongly than the other pole. As a result, Earth’s magnetic field pulls the needle toward the ground.

Flat-Earthers claim that a compass is unusable only near Antarctica. In reality, the same also occurs near the North Pole. Magnetic dip, as observed on various locations on Earth, can only happen if the Earth is spherical.

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“Stuff is Flat”: Incorrect Neil deGrasse Tyson’s Claim About the Observation of Earth’s Curvature

Neil deGrasse Tyson once incorrectly stated that it is still too close to the surface to see Earth’s curvature from the height of Felix Baumgartner’s jump. In reality, we should be able to see it using our eyes.

Flat-Earthers believe people take Neil’s remarks as gospel and use Neil’s incorrect statement to dismiss any observation of Earth’s curvature. However, we have no problem saying that Neil was wrong. It is OK to be wrong as long as we are willing to revise our views when faced with new facts, and we are certain Neil will.

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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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Invalid Hypothesis for the Observation of a Distant Object

Flat-Earthers love to observe the visibility of a distant object. But the observation can never prove Earth is flat.

The observation of a distant object can only go as far as to disprove Earth is a sphere with a radius of 3959 miles. A flat Earth is merely one of the so many possibilities, but it is still possible the Earth is a sphere, only much larger.

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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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