### Temperature Variations at the Different Times During the Day

The variation of the temperature at the different times during the day is the result of two primary causes: the difference of the thickness of the atmosphere the sunlight must traverse to reach the surface; and the change of the concentration of sunlight over the same surface area of the Earth.

Flat-Earthers claim that the change in Sun’s distance caused such a difference in temperature and that it can only be explained in a flat Earth. They are wrong.

### The Gleason Map

The “Gleason Map” is a map with the azimuthal equidistant projection, centered on the north pole. The Gleason Map is not a scaled-down figure of the Earth, but it is merely a projection of the actual, spherical shape of the Earth, like every other map.

Alexander Gleason —the creator of the map— claimed that the map depicts the shape of the ‘flat Earth’. The majority of the flat-Earth communities adopt this map as ‘the flat-Earth map.’ They are wrong. The map is merely a projection of the spherical shape of the Earth, just like every other map types.

### The Foucault Pendulum Proves Spherical and Rotating Earth

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.

### Quote Mining: How They Misrepresent Facts and Attempt to Incite Us

A favorite modus operandi of flat-Earth perpetrators is quote mining, or quoting out of context. They would read statements from scientists and watch their videos, then look for words they can use out of the intended context and spread them.

To some people, these scientists would appear contradicting each other and that there is never a consensus in science. They would even go as far as portraying the scientists as having some evil intentions to deceive us. In reality, the information no longer resembles what the scientists had in mind.

### Polaris is not Stationary in the Sky

Polaris is a bright star that is close to the north celestial pole. Currently, Polaris is only 0.74° apart from the north celestial pole and the only star visible to the naked eye that is close to the celestial pole. This is why Polaris is popular as a navigational aid in the northern hemisphere.

Some flat-Earthers think that Polaris is stationary and that it is a ‘special star’ because other stars are in motion around it. They would take that as ‘evidence’ that the Earth is motionless. They are wrong. Polaris is merely a regular star, just like the others.

### The Earth is Really Spherical, Not Because “NASA Told Us So”

The fact that the Earth is spherical was known since at least 3rd century BC, or about 24 centuries ago, far before we can send anything to space. We knew the fact from countless observations, and not merely from photos and videos taken from space, or that “NASA told us so.”

On the other hand, flat-Earthers often mention NASA or other space agencies because they don’t have a choice. If they insist on the wrong notion that the Earth is flat, then they would need to invent various excuses why there are photos and videos taken from space.

### Sunglint

Sunglint is a phenomenon that occurs when sunlight reflects off the surface of a water body —like the ocean— at the same angle as an observer is viewing the surface. In the affected area, relatively smooth ocean water becomes a silvery mirror.

In the flat-Earth model, the Sun is assumed to be a ‘local light source.’ They like to use a spotlight or a flashlight as an analogy. They present the sunglint phenomenon as ‘evidence’ of the fact that sunlight is local. They are wrong.

### Kettle Logic: Conflicting ‘Explanations’ in the Flat-Earth Model

Kettle logic is making multiple contradicting arguments in an attempt to support a single point or idea.

Kettle logic occurs very frequently in the flat-Earth community. If they meet a natural phenomenon cannot readily be explained using the flat-Earth model, they would often devise ‘experimental models’ to ‘explain’ how the said phenomenon can happen in a flat-Earth.

The problem? These models are in conflict with each other.

### Total Lunar Eclipse, Drawn to Scale

Any diagram showing two or more celestial bodies is almost never drawn in the correct scale. The reason is that in most cases, any two celestial bodies are spaced too far away relative to their sizes. It is just not possible to draw them in the correct scale and still effectively describes what we want to explain. We don’t have much choice other than drawing them not to scale.

The perpetrators of flat-Earth disseminate the allegations that the diagrams were drawn not to scale because of evil intentions, and not because of legitimate technical reasons. Some people don’t understand this and fell victim to flat-Earth indoctrination.

### Phases and Side of the Moon

In the real world, the Moon is spherical. It doesn’t emit its own light; it gets its light from the Sun. The Moon is tidally locked, causing one side of it to be permanently turned towards the Earth. The lunar phase occurs because of the change in the position of  Sun-Earth-Moon with respect to each other.

Any flat-Earth model fails to explain many Moon-related phenomena. Flat-Earthers who insist on defending their misguided flat-Earth concept at all costs are forced to invent many “explanations” on how Moon-related events might happen on a flat-Earth.

Simple observation tells us that we always see the same side of the Moon, but the phase changes in a month-long cycle. These facts rule out the majority of the “explanations” invented out of thin air by flat-Earthers, including the “Moon emits its own light”, “half-sphere Moon” and the “transparent Moon” explanations.

## References

### 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.

### The Moon in Daytime and the ‘Transparent Moon’ Misconception

Earth’s atmosphere scatters sunlight in every direction. Bluish colors are scattered stronger than reddish tones. As a result, the sky is glowing in bright blue during the day. The phenomenon is called the Rayleigh scattering.

Sometimes the Moon is visible during the day. The bright part of the Moon is bright because it is lit by the sunlight. On the other hand, its dark part does not receive sunlight, and thus barely emit any light. Because of these reasons, the dark part of the Moon is dominated by the blue color of the sky.

### Day and Night Areas on a Flat Earth

At any given time, there is an equal area of the Earth that is experiencing daytime, and that is having a night time. The reason is that the sun is very far, and it would illuminate a hemisphere of the Earth, and leave the other dark.

If we plot which areas of the Earth that are getting sunlight on an azimuthal equidistant map centered on the north pole, the sun would appear to illuminate a somewhat elliptical area during the northern hemisphere summer, and a lopsided Bat-Signal shaped area during the winter. During the equinox, the sun would appear to illuminate a half-circle area.

### Density and the Balance Experiment

An object falls down because of Earth’s gravitational attraction. But some denominations of flat-Earth insist that an object falls down due to its density, not gravity.

By putting two objects of an equal density and different mass against each other using a balance, we can easily determine that the density of the object is not the reason it falls down.

### 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.

### Satellite Watching

It is not hard to spot satellites. Satellites can easily be seen under the following conditions:

1. They are easier to see the larger and the closer they are.
2. The darker the sky, the easier to see them.
3. Satellites are visible only when they are lit by the sunlight.

Because of these conditions, satellites are usually seen a few hours after sunset or a few hours before sunrise.

Flat-Earthers claim that satellites can never be seen, and the fact is evidence that “satellites don’t exist”. They are wrong. Satellites can easily be seen under the right conditions.

### Total Solar Eclipse, Drawn to Scale

Any diagram showing two or more celestial bodies is almost never drawn in the correct scale. The reason is that in most cases, any two celestial bodies are spaced too far away relative to their sizes. It is just not possible to draw them in the correct scale and still effectively describes what we want to explain. We don’t have much choice other than drawing them not to scale.

The perpetrators of flat-Earth disseminate the allegations that the diagrams were drawn not to scale because of evil intentions, and not because of legitimate technical reasons. Some people don’t understand this and fell victim to flat-Earth indoctrination.

### The Phase of the Moon and a Ball

The phases of the Moon depends on the position of the Moon relative to the Earth and the Sun. They occur because the Moon is spherical & lit by sunlight and that the Sun is very far away. Both imply that the Earth is spherical too.

The phases of the Moon according to observation cannot be explained in any flat-Earth model. Flat-Earthers had to invent various explanations to explain how the lunar phases can happen in the flat-Earth model. None can explain how a ball has the same phase as the Moon when seen from the same direction as we see the Moon.

### The Hyman’s Maxim

The Hyman’s Maxim says:

“Do not try to explain something until you are sure there is something to be explained.”

We can apply this maxim to a lot of situations involving flat-Earthers, and avoid wasting our time.

### 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.