Diurnal motion is the apparent daily motion of stars around the two celestial poles due to Earth’s rotation. The stars move in a peculiar way that can only be explained in the spherical Earth model.
All the differences of diurnal motion that occur in the different latitudes on can never be explained in a flat Earth.
Continue reading “Diurnal Motion – Possibly the First Evidence of Spherical Earth”
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.
Continue reading “The Distance to Polaris”
If a satellite has the orbit of 35786 km above Earth’s surface, the satellite will be in motion at the same speed as the Earth’s rotational rate. As a result, the satellite will appear practically motionless when observed from the surface. Many communication satellites reside in this orbit, and a satellite dish receiving signals from the satellite does not 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’ the dishes cannot be pointing to satellites. They are wrong.
Continue reading “Geostationary Satellites”
A cyclone or hurricane rotates in a different direction depending on which hemisphere it occurs. A cyclone rotates counterclockwise in the Northern Hemisphere, and clockwise in the Southern Hemisphere.
The phenomenon happens because of the Coriolis effect, which in turn occurs because the Earth is spherical and rotating.
Continue reading “Cyclonic Rotation: The Direction a Cyclone or Hurricane Rotates”
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.
Continue reading “Velocity is Measured From Specific Frame of Reference”
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 is the apparent shift of the position of any nearby star against the background of distant stars. It is the result of Earth’s orbital motion around the Sun. It is so small and hard to observe. Successful measurement of stellar parallax was done only after the 19th century.
Some flat-Earthers presume as if stellar parallax has not been successfully observed, and use it is ‘evidence’ the Earth is stationary. They are wrong.
Continue reading “Stellar Parallax”
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.
Continue reading “The Aether Experiments are Never Evidence of Flat and Stationary Earth”
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.
Continue reading “Polaris: Our Current North Pole Star, But Not For Forever”
Eötvös effect is the change in perceived gravitational acceleration when moving eastward vs westward. An object will weigh more when moving westward than when it is stationary or moving eastward.
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.
Continue reading “Eötvös Effect: Evidence of Spherical, Rotating Earth”
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.
Continue reading “Lunar Phase and Lunar Eclipse”
In the northern hemisphere, if we look at the sky to the north, we can observe stars rotate counter-clockwise around a point. This axis of rotation is not visible from observers in the southern hemisphere.
On the other hand, in the southern hemisphere, if we look at the sky to the south, we can observe stars rotate in the opposite direction. Conversely, this axis of rotation is not visible from observers in the northern hemisphere.
This motion of the stars cannot possibly happen in a flat-Earth. The motion of the stars is a proof that the Earth is round and rotates around its axis.
Continue reading “Star Trail: Evidence the Earth is a Sphere and Rotating Around Its Axis”
‘The Principle’ is a pseudoscientific documentary that promotes geocentrism, that the Earth is stationary and the center of the universe. Despite the fact that the film has almost nothing to do with flat-Earth, some flat-Earthers decide to use this film to bolster their beliefs. Because after all, in the flat-Earth model, the Earth is stationary and the center of the universe, right?
This actually gets more complicated than that. We are dealing with two forms of pseudoscience, that sometimes even goes against each other.
Continue reading “‘The Principle’: A Documentary Without Principle”
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.
Continue reading “Midnight Sun in Both Polar Regions Proves Spherical Earth”
The mass of the Earth exerts the gravitational acceleration of about 9.79 m/s² to everything on Earth’s surface toward the center of the Earth. On the other hand, the rotational motion of the Earth generates the centrifugal acceleration of about 0.03 m/s² away from the Earth. The net acceleration is about 9.79 m/s² toward the center of the Earth. That is why everything on Earth’s surface stays on the surface, not flying away to space.
Flat-Earthers often make a false comparison using a wet spinning ball. Water on the surface of a wet spinning ball does not stick to the ball; but the Earth is also round, wet and spins, yet everything stays on the surface. Then they make the erroneous conclusion that the Earth cannot be a spinning ball.
Continue reading “The False Analogy of a Spinning Tennis Ball”