Geostationary Satellites

A satellite can be placed in an orbit 35786 km above Earth’s surface, and the satellite will be in motion at the same speed as the rotation of the Earth. As a result, the satellite will appear practically motionless when observed from the surface.  Many communication satellites are placed in this orbit, and a satellite dish receiving signals from the satellite doesn’t have to track the satellite.

Flat-Earthers often take the fact that satellites are in motion and most satellite dishes have a fixed direction as ‘proof’ there’s something suspicious about satellites. They are wrong.

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Velocity is Measured From Specific Frame of Reference

A widespread misunderstanding within the flat-Earth victims is related to velocity/speed. They seem to think velocity is absolute, while in reality it is measured from a specific frame of reference. Example:

“If the Earth is in motion around the Sun at 30 km/s, and Apollo traveled at only 11 km/s, then how could Apollo astronauts possibly make it back to the Earth?”

We used to measure velocity/speed relative to the surface of the Earth. But it is not always like that.

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Annual Stellar Motion: Evidence of Earth’s Orbit Around the Sun

In each day, we can observe stars drift about 1° in their movement around the celestial pole. In a month, they will appear to have moved about 30° when observed at the same time in the night. And in a year, stars are back to their original positions precisely a year before. This annual stellar motion is the basis for the calendar system we are using.

Some flat-Earthers think we see the same star constellations every night. From this assumption, they would conclude the Earth is stationary. But their claim is demonstrably wrong. Continue reading “Annual Stellar Motion: Evidence of Earth’s Orbit Around the Sun”

Stellar Parallax

Stellar parallax is the apparent shift of the position of any nearby star against the background of distant stars. It is caused by Earth’s orbital motion around the Sun. It is so small and hard to observe. Successful measurement of stellar parallax was done only after 19th century.

Flat-Earthers like to think stellar parallax doesn’t exist, and that it is ‘evidence’ the Earth is stationary. They are wrong.

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The Aether Experiments Are Not Evidence of Flat and Stationary Earth

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, there were experiments that attempted to prove if the aether actually exists.

Flat-Earthers (and geocentrists alike) often use the results of these experiments in order 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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Our Ability to Perceive Speed and Acceleration

When we are aboard a plane flying at cruising speed, we will not be able to feel that the plane is in fact moving at speed of more than 900 km/h. But if the plane changes speed, turns or changes its altitude, we can easily feel it.

Same thing happens with the motion of the Earth. Because of the Earth’s rotation, the surface of the Earths moves at a speed of 1656 km/h near the equator. It also travels around the Sun at a speed of about 107000 km/h. We never feel any of these because the speed is constant, or in other words, the acceleration is zero.

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Polaris: Our Current North Pole Star, But Not For Forever

Flat-Earthers often claim that the fact Polaris not appearing to move is ‘evidence’ that the Earth is flat and stationary. If the Earth is a rotating sphere, then Polaris —as they say— should appear to be in motion.

In reality, Polaris is indeed moving across the sky. Though it is not something we can observe in a single night, or even in our entire lifetime.

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Eötvös Effect: Evidence of Spherical, Rotating Earth

Eötvös effect is the change in perceived gravitational acceleration when moving eastward vs westward. An object will weigh more when moving eastward than when it is stationary or moving westward.

The effect was discovered by Loránd Eötvös in the 1900s after noticing the difference in gravity measurement on moving ships. He noticed that the readings were lower when the boat moved eastwards, higher when it moved westward. He identified this as primarily a consequence of the rotation of the Earth.

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Lunar Phase and Lunar Eclipse

Apparently it is a very common misconception that the phases of the Moon is caused by the Earth’s shadow. Not only among flat-Earthers, but the general public as well. The difference is that flat-Earthers will usually jump to conclusion, and have some outlandish interpretation about this.

In reality, the phases of the Moon happen because we see a different sunlit part of the Moon at different time. Not because it is over the shadow of the Earth.

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