Airplane and Earth’s Rotation

An airplane exists on Earth. It has the same motion as the surface of the Earth, including the Earth’s rotating motion. The motion of the airplane itself is measured relative to the surface of the Earth.

Flat-Earthers think that due to Earth’s rotation, an airplane should not be able to fly east or land. They are wrong. The speed of an airplane is relative to the surface. It retains the motion of the Earth and does not need to chase Earth’s rotation.

Continue reading “Airplane and Earth’s Rotation”

Einstein’s Thought Experiments and Daydreaming

Albert Einstein used thought experiments as a tool for formulating his theories. His theories provided predictions that can be tested in observation and experiments. He did not perform the observation and experiments himself. Others did and confirmed his theories.

Some flat-Earthers dismiss Einstein’s theories —especially those about gravity— on the basis that they are founded on thought experiments and daydreaming. They are wrong. His theories have been repeatedly confirmed by various experiments and observation performed by many others, even to this day.

Continue reading “Einstein’s Thought Experiments and Daydreaming”

Magnetic Poles

Every magnet has a north pole and a south pole. The opposite poles of the different magnets attract each other, while the same poles of the different magnets repel each other. It is not possible to have a magnet with a single pole.

Flat-Earthers proclaim that Earth cannot be a sphere because if a compass really points to the north pole, then on the equator, it should point 45° downward. They are wrong. A magnet does not only have the north pole, but it also has the south pole which is attracted to the north pole of Earth’s magnetic field. Near the equator, both forces are balanced and pull the compass’ needle to both Earth’s poles at the same time. A perfectly balanced compass will be level near the equator.

Continue reading “Magnetic Poles”

Lunar Phase: Earth’s Shadow has Nothing to do with It

It can be surprising that many people believe that the lunar phase is caused by the Earth casting its shadow on the surface of the Moon. Flat-Earthers are no exception. But they take it one step further and use the misconception do “disprove” the fact that Earth is a sphere. They are wrong. The lunar phase is the shape of the sunlit part of the Moon seen from the observer.

On the other hand, the phenomenon where the Earth casting its shadow on the surface of the Moon is called the lunar eclipse. Moon phase occurs all the time and undergoes a monthly cycle, while a lunar eclipse happens only a couple times in a year.

Continue reading “Lunar Phase: Earth’s Shadow has Nothing to do with It”

Cavendish Experiment

The Cavendish experiment was the first experiment to measure the force of gravity between masses in the laboratory and the first to yield accurate values for the gravitational constant.

Flat-Earthers are in a constant effort to discredit the Cavendish experiment. They would invent various “explanations” to “explain” the result of the experiments. However, the experiment was not only done once by Henry Cavendish in 1797-1798, and has been replicated numerous times by multiple independent parties for centuries, all yielding consistent results.

Continue reading “Cavendish Experiment”

Rayleigh Scattering

Earth’s atmosphere glows in blue because of Rayleigh scattering. It scatters sunlight to every direction. Bluish colors are scattered more than reddish colors. This results in the bright blue color of the sky in the daytime.

There are many misconceptions in the flat Earth community that arise from the lack of understanding of Rayleigh scattering.

Continue reading “Rayleigh Scattering”

Weight = Gravitational Force

The weight of an object is the force exerted on the object by gravity. The gravitational force exerted by the Earth on an object is what we refer to as ‘weight’.

Many flat-Earthers fail to understand that the gravitational force is just another name for ‘weight’. Many misconceptions in the communities of flat Earth victims arise from such a misunderstanding.

Continue reading “Weight = Gravitational Force”

Horizontal Motion of Smoke

Smoke rises due to convection current. The solid particles emitted from a combustion process are carried by the hot air that rises because of its lower density than the surrounding air. The horizontal motion of smoke itself is affected by the movement of air surrounding it.

Flat-Earthers claim that a rising smoke without horizontal motion “proves” a stationary Earth. They are wrong. The horizontal motion of smoke is an effect of the horizontal motion of air relative to the smoke, and the motion of the object emitting the smoke is inconsequential.

Continue reading “Horizontal Motion of Smoke”

Frame of Reference

A frame of reference consists of an abstract coordinate system and the set of physical reference points that uniquely fix the coordinate system and standardize measurements. Speed or velocity is relative to a frame of reference. It is possible that two speeds/velocities are measured relative to a different frame of reference and thus cannot be directly compared.

Flat-Earthers would often compare two different speed measurements like an airplane moving at 900 km/h (560 mph) and Earth’s surface near the equator at 1674 km/h (1040 mph). They would conclude the airplane should not be able to catch up with Earth’s surface and would not be able to land if the Earth is rotating. They are wrong. The speeds are measured relative to the different frame of reference, and therefore, cannot be compared directly.

Continue reading “Frame of Reference”

The Dark Sky on the Lunar Daytime

On Earth, daylight sky is glowing in bright blue due to Rayleigh scattering. Sunlight is scattered in every direction by the oxygen and nitrogen molecules in Earth’s atmosphere.

Such the phenomenon does not happen on the Moon, causing the dark sky of the Moon. Flat-Earthers claim that the dark sky of the Moon captured by photos and videos taken from the Moon are “proof” there is misconduct. They are wrong. Just because Earth’s sky is bright blue, it does not mean it will be like that on the Moon and other planets.

Continue reading “The Dark Sky on the Lunar Daytime”

Determining the Visibility of a Star From Its Declination and the Observer’s Latitude

We can determine if a star is visible from a specific location using the declination of the star and the latitude of the observer, subject to other conditions like observer’s topology, the magnitude of the star, weather conditions, etc. It is possible to do this because Earth is a rotating sphere.

If the Earth is flat, every star would have been visible all night from every location. We don’t see the same stars every night because some of them are below the horizon and obscured by the Earth.

Continue reading “Determining the Visibility of a Star From Its Declination and the Observer’s Latitude”

Earth’s Atmosphere Rotation

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.

Continue reading “Earth’s Atmosphere Rotation”

Theories of Gravity

Gravity is a natural phenomenon by which all things with mass or energy are brought toward one another. Today, the phenomenon of gravity is explained by two theories: Newton’s law of universal gravitation and Einstein’s general relativity.

Flat-Earthers take the existence of the two explanations as inconsistency in science and use it as a “proof” of deliberate misconduct. Such allegation is obviously only a result of their prejudice. The two theories are the correct explanations of gravity, and can reliably predict the outcome of the phenomenon.

Continue reading “Theories of Gravity”

Buoyancy

Buoyancy is an upward force exerted by a fluid (liquid or gas) that opposes the weight of an immersed object. Buoyancy happens because the fluid has a pressure gradient. Pressure gradient occurs because the fluid is affected by acceleration, such as the Earth’s gravitational acceleration.

Flat-Earthers makes buoyancy as an “explanations” on how things fall. They are wrong. Without Earth’s gravitational acceleration, buoyancy will not occur.

Continue reading “Buoyancy”

Circumpolar and Non-Circumpolar Stars

A circumpolar star is a star, as viewed from a given latitude on Earth, that never sets below the horizon due to its apparent proximity to one of the celestial poles. Circumpolar stars stay up there in the sky, even during the day.

Flat-Earthers claim the Earth is stationary because the same stars are always visible in the sky. They are wrong. Only circumpolar stars are always in the sky. There are others that are not circumpolar. Some are only visible during certain times in a year.

Continue reading “Circumpolar and Non-Circumpolar Stars”

Sun Path

In the Northern hemisphere, the Sun appears to move to the right. In the Southern hemisphere, it appears to move to the left. During sunrise and sunset, the path of the Sun forms an angle that roughly corresponds to the latitude of the observer. This phenomenon occurs because observers on the different locations on Earth’s surface is not standing on the same plane.

The path of the Sun observed from many different locations on Earth’s surface is evidence of spherical Earth. This observation cannot possibly occur on a flat Earth.

Continue reading “Sun Path”

Countering Gravity

Gravity is not the only force. There are other forces, too. Multiple forces can simultaneously affect a single object. Forces can counteract gravity, making an object move against the direction of gravity. Such facts do not disprove gravity.

Flat-Earthers take the fact there are objects that move against the direction of gravity as ‘evidence’ of the non-existence of gravity. They are wrong. There are forces other than gravity affecting the object, having the opposite direction from gravity, with at least the same magnitude.

Continue reading “Countering Gravity”

Newton’s Law of Universal Gravitation

Gravity is a natural phenomenon by which all things with mass or energy are brought toward each other. In 1687, Isaac Newton explained the phenomenon as a force, which was formulated in Newton’s law of universal gravitation.

Flat-Earthers insist that gravity does not exist. But this is only a result of a mere ignorance on how gravity works. Everything in our lives is consistent with what is explained in Newton’s law of universal gravitation.

Continue reading “Newton’s Law of Universal Gravitation”

Geometry of a Full Moon

Some people are confused that a full moon is visible all night, and think if the full moon is the result of the opposition of the moon from the sun, then a full moon should be visible only at midnight.

Flat-Earthers who have such spatial visualization problem take a step further and use it as ‘evidence’ that the Earth is not a sphere. They are wrong. The full moon phenomenon can easily be explained in the spherical Earth model.

Continue reading “Geometry of a Full Moon”

Helicopter and Earth’s Rotating Motion

We cannot travel to another location by hovering inside a helicopter and wait for the Earth to rotate below us until we are above our destination. The reason is the phenomenon of inertia.

Flat-Earthers claim that we cannot do such a thing as ‘proof’ of a motionless Earth. They are wrong. When on the ground, the helicopter itself is already moving at the same velocity as Earth’s surface.

Continue reading “Helicopter and Earth’s Rotating Motion”