Curvature of the Horizon in High-Altitude Balloon Footage

High-altitude balloon footage is often abused by flat-Earthers to show us that the Earth is flat when seen from a high altitude.

We analyzed more than two dozens of footage taken from high-altitude balloons on YouTube, and we can easily conclude the curvature is there and usually easy to spot, including in the cases where flat-Earthers use the video as ‘proof’ of a flat Earth.

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The Curvature of the Water Surface

Flat-Earthers mention the curvature of water a lot. According to them, the curve of the water can never be observed, and thus, the Earth is flat.

The problem with such an argument is that they usually conclude that from a very small amount of water. Water in a glass or a bucket will practically look flat. Not because there is no curvature due to Earth’s gravity, but because the water is in such small amount so that the curvature is minuscule and impossible to observe, let alone with the naked eye.

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Equipotential: a Property of the Surface of Water

Gravity causes water to seek the lowest potential, which can be simplified as the position as close as possible to the Earth’s center of gravity. As a result, the surface of the water will have equipotential surface and form an approximately spherical surface which has the same center as the Earth. Every location along the surface has the same potential.

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Bedford Level Experiment Confirmed the Curvature of the Earth

In 1870, Alfred Russell Wallace successfully demonstrated the curvature of the Earth to answer the challenge put forward by a flat-Earther, John Hampden.

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Long-Range Wi-Fi and the Curvature of the Earth

Wi-Fi is one of the most common ways of getting connected to the Internet. Practically all short-range wireless network use WiFi. Using specialized equipment, Wi-Fi is usable over a very long distance, even over hundreds of miles.

When designing a long-range Wi-Fi link, we must account for the curvature of the Earth.

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Archimedes and the Surface of any Fluid

Archimedes is a scientist from 3rd century BC. He is best known for the Archimedes’ Principle which explains buoyancy. He also contributed to many scientific discoveries and inventions.

But did you know that Archimedes explained the Archimedes’ principle using the spherical Earth model?

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Lake Pontchartrain Power Transmission Lines: Evidence of Earth’s Curvature

Lake Pontchartrain is a lake in Louisiana, United States. There are power transmission lines about 24.27 km (15 mi) across this lake. They are practically straight, and each tower is uniform and has the same height, making these towers ideal for observing the curvature of the Earth.

They were first popularized by Soundly who presented evidence of Earth’s curvature using a series of photos and videos of the power lines in June 2017. As of now, the towers and other objects on the lake are probably the most popular Earth curvature tourism spot in the world.

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Surface of Water and Communicating Vessels

Gravity is not the result of a particular shape of an object. It is caused by mass. All objects with mass exert gravity to each other. The larger the mass of an object, the greater the force of gravity.

On Earth, water forms a spherical surface which has the same center as the Earth. It applies to every surface of fluid which is under influence by Earth’s gravity, unaffected by another force. In a 10 cm wide container, the amount of curvature is only 0.0000002 mm. It is the reason the surface appears flat in small containers.

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The Little Piggy Balloon Footage Proves Earth is a Sphere, not Flat

Little Piggy is the nickname of a helium balloon launched by IndianaCaver. It reached the altitude of almost 37 km before it finally ruptured and fell to the Earth. Before that, it took several hours of video, and IndianaCaver made these video available on YouTube.

Then, some flat-Earthers cherry-picked bits of the video where the horizon looked flat and presented it as ‘proof’ of flat-Earth. These are widely circulated in various memes and forms, even years after the originals were published.

But, can we use these videos as ‘proof’ of flat-Earth?

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Sunset at Burj Khalifa

Having the total height of about 830m, Burj Khalifa is the tallest building in the world. It is so tall that we can observe the sunset at the base of the building, then rush to the upper floors and watch the same sunset again for the second time on the same day.

This phenomenon can only happen if the Earth is a sphere. On a higher position, we will observe the sunset later than when we are closer to the ground.

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Fisheye Lenses and Earth Curvature

A good majority of pictures of Earth taken from space are being dismissed by flat-earthers merely because they are made using fish-eye lenses. They believe any curvature of Earth shown in those pictures is the result of the fisheye effect, and thus, cannot be used as evidence of Earth’s curvature. They even take a step further and assume a fish-eye lens is deliberately used to take every picture of the Earth taken from a high altitude so that they would have a curvature in it.

These claims are, of course, ungrounded. In some cases, we can conclude the curvature is there, even when a fish-eye lens is being used. We can use this useful property of any photographic lens:

A straight line will appear straight as long as it crosses the center point of the image.

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So, Where’s the Curvature?

A human eye can only visually perceive the curvature of the Earth if we are at a considerable altitude from the surface, which is still beyond the reach of most humans today. A commercial jet airliner is the highest position realistically attainable by most humans today. At such altitude, we can only perceive very slight curvature, and only in an ideal condition.

The basis of flat-Earthers’ belief is that the horizon appears flat. They would say if we cannot see the curvature, then there’s no curvature, and thus, the Earth is flat. They are wrong. Most of us these days cannot travel high enough to see the curve.  The best we can do these days is going on board a commercial jet airliner, which can only go about 11-15 km up, only a fraction of the radius of the Earth.

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