The Angle of a Shadow During Equinox

During an equinox (March 20 and September 22-23), the Sun is directly above the equator. If we are on the equator, an upright stick will not have a shadow in the middle of the day.

On any other location, the angle between the stick and the direction of sunlight will be the same as the observer’s latitude.

This fact can only occur if the Earth is a sphere, and only if the Sun is very far relative to the size of the Earth.

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Schiehallion Experiment

The Schiehallion experiment was an experiment to determine the mean density of the Earth. It involved measuring the tiny deflection of a pendulum due to gravitational attraction from the mountain of Schiehallion, Scotland. The measured deflection was 11.6″ or 0.003°.

Flat-Earthers claim that it is impossible to demonstrate gravity and that it is evidence gravity does not exist. They are wrong. The Schiehallion experiment was one of the first practical experiments of gravity done on Earth.

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Determining the Distance to the Sun from the Transit of Venus

The distance to the Sun was first determined with a good accuracy from worldwide observations of the transit of Venus. A transit of Venus is a phenomenon where Venus passes in front of the Sun. By measuring the time Venus spends crossing in front of the Sun from two or more locations on the surface of the Earth, it is possible to calculate the distance to the Sun.

Flat-Earthers insist that it is impossible to determine the distance to the Sun in the globe model because sun rays are practically parallel. They are wrong. Using simple geometry, the distance to the Sun can be determined from the observations of the transit of Venus.

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The Apparent Size of the Sun

The apparent size of the Sun is practically constant throughout the day. This can only happen if the Sun is practically at the same distance all day.

In the flat-Earth model, the Sun is close to the surface at the distance of about 5000 km (3500 miles). The Sun is supposed to be moving in a circle, and it completes the circling motion once in a day. This fact should cause the Sun’s apparent size to change during the day. But it does not happen. The Sun’s constant apparent size is evidence that the flat-Earth model is wrong, and that the Sun is very far away.

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Seismic Waves: Mapping the Interior of the Earth

Seismic waves are waves of energy that travel through the Earth’s layers and are a result of earthquakes, volcanic eruptions, massive landslides and large human-made explosions. Some types of seismic waves travel through the interior of the Earth and are detected by seismic stations on the other side of the Earth. By analyzing the types of waves that are received by seismic stations, we can determine the interior of the Earth.

Flat-Earthers are often seen saying that it is impossible to determine the interior of the Earth as nobody has gone there. They are wrong. Using seismology, we can determine the interior of the Earth without going there physically.

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Fraunhofer Lines

Sunlight can be broken into its constituent colors using a prism. The colors are the optical spectrum of the Sun. They are the same colors on rainbows. On careful observation, the spectrum is not perfectly continuous, but it has dark lines scattered over the entire spectrum. It turned out that from the lines, we can tell the composition of the Sun without physically getting there.

Some flat-Earthers think that it is impossible for us to determine the composition of the Sun, as it is impossible for anyone to visit the Sun without getting roasted in the process. They are wrong. The composition of the Sun can be determined from the spectral lines, or more specifically for the Sun: the Fraunhofer lines.

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The Distance to Polaris

Anyone who is in the northern hemisphere can observe the star Polaris, located very close to the north celestial pole. As a result, when observed casually, Polaris appears practically stationary in the same position.

Flat-Earthers claim that the fact Polaris appears stationary as ‘evidence’ that the Earth is stationary: if the Earth is in motion, then Polaris should appear in motion too. They are wrong. Polaris appears stationary because it is very far and its motion can’t be visually observed in the scale of a human life.

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Proper Motion

Proper motion is the apparent motion of stars, caused by the movement of the stars themselves, relative to the solar system. Stars will appear to shift over time, relative to other, more distant stars.

Flat-Earthers assume stars are only in motion around Polaris, or the north celestial pole. They are wrong. Stars have other apparent motions, one of which is proper motion.

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How the Sun ‘Burns’ Without Air in Space

A candle gets its flame from combustion, a chemical reaction. The hydrocarbon that formed the candle reacts with oxygen, and we get carbon dioxide, water, and heat energy as the results. The oxygen is obtained from the air. If the air supply is cut off —for example by covering the candle with a glass— then the reaction will stop, and the flame goes out.

We hear flat-Earthers often claimed that it is impossible for the Sun to be in space. They said the Sun burns, and therefore it requires oxygen. Space is empty, so it is impossible for the Sun to be there. They are wrong. The reaction that is occurring in the Sun is not combustion. It works differently from what happens with the candle.

Nuclear fusion powers the Sun.  It fuses hydrogen atoms into helium atoms. All the necessary component for the reaction to happen is in the Sun, and the reaction doesn’t require matters from external sources.

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