The gravitational acceleration exerted by the mass of a wet, spinning tennis ball is too small compared to the centrifugal acceleration generated by its rotating motion. As a result, the water escapes away from the tennis ball, unlike Earth.
A wet spinning ball is a sphere, spinning & wet, like Earth. But the water goes away from the ball, unlike Earth. Flat Earthers use it to “disprove” spherical Earth. In reality, the magnitude of the involved accelerations in the two cases are different.
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Because of inertia, we cannot travel to another location by hovering inside a helicopter and waiting for the Earth to rotate below us until we are above our destination.
Flat-Earthers claim that we cannot do such a thing as ‘proof’ of a motionless Earth. In reality, when still on the ground, the helicopter is already moving at the same velocity as Earth’s surface.
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An airplane exists on Earth. It has the same motion as the surface of the Earth, including Earth’s rotating motion. The motion and speed of an airplane are measured relative to Earth’s surface.
Flat-Earthers claim that an airplane should not be able to fly eastward or land. In reality, an airplane is moving relative to the surface. It has Earth’s motion as a component of its motion and does not need to chase Earth’s rotation.
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The Earth rotates only once every 24 hours. To notice the rotation of Earth in a video taken from space, we need to speed up the video so that it appears fast enough for us to notice it. We also need to make sure the video was taken from a spacecraft where its motion does not dominate over the movement of Earth itself.
Flat-Earthers claim that videos taken from space were faked because the Earth does not appear rotating. In reality, Earth rotates far too slowly to be casually seen without increasing the speed.
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Eötvös effect is the change in perceived gravitational acceleration when moving eastward vs. westward. An object will weigh slightly more when moving westward than when it is stationary or moving eastward.
The slight difference in weight due to the Eötvös effect can be measured in an experiment on a flight. The Eötvös effect is direct evidence that the Earth is a rotating sphere.
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Earth’s atmosphere is part of the Earth. It practically follows Earth’s rotating motion like the rest of the Earth. Due to various factors, Earth’s atmosphere has relatively small and uneven movement relative to the surface. We call it ‘wind.’ The fastest wind ever recorded is about 408 km/h, relative to Earth’s surface.
Many misconceptions about Earth arise from the wrong idea that only Earth’s solid body is rotating, but the atmosphere is not. If it is true, then we should always feel the wind with the speed of 1674 km/h near the equator, or more than 4× the fastest wind ever recorded. We don’t feel such a wind, and thus we know our atmosphere is moving at practically at the same speed as Earth’s surface.
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The Foucault Pendulum is an experiment to demonstrate Earth’s rotation, named after French physicist Léon Foucault. The Foucault pendulum is the first simple and direct evidence of the Earth’s rotation. It is a straightforward experiment: a huge pendulum is allowed to swing throughout the day, and it will slowly rotate because of Earth’s rotation.
For any flat-Earthers, the Foucault pendulum is one of the facts that must be discredited. They would invent various “explanations” to reject the conclusion of the experiment. They are wrong. Anyone is free to repeat the experiment, and when done correctly, it will result in a consistent result and in line with expectations.
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Aether was the hypothetical material that fills the region of space. It was assumed to be the medium that allows light and gravity to propagate in space. Throughout the late 1800s and early 1900s, some experiments were carried out to prove if the aether exists.
Flat-Earthers (and geocentrists alike) often use the results of these experiments to support their case that the Earth is stationary. But they are wrong. These experiments were conducted to prove if the Aether theory, or if one of its competing hypotheses —like the Special Relativity— better explains reality.
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Midnight Sun is a phenomenon where the Sun remains visible at midnight. This phenomenon occurs in the summer months north of Arctic Circle, and south of the Antarctic Circle.
The apparent motion of the Sun in both polar regions is different. In the north polar region, the Sun moves from left to right. On the other hand, in Antarctica, the Sun moves from right to left. There is no explanation other than that Earth is a sphere.
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