How To Debate A Flat Earther

If check around the internet and your neighborhood, you will see many people that believe in flat Earth theory. Hence, spotting a flat Earther is not that difficult. These people inherited this belief from numerous ancient cultures that suggest that the Earth is flat. The reason why ancient cultures believed in a flat Earth is because they were not advanced enough to realize that we are truly living on a spherical Earth.

But despite centuries of evidence proving that the Earth is not flat, millions of people still share similar beliefs with ancient cultures. Why do people believe that the Earth is flat? How can you debate a flat Earther? Continue reading to see concrete evidence that you can use to convince a flat Earth that we are not living on a flat Earth.

How to debate A flat Earther

Scientists have conducted numerous observations, experiments, and demonstrations to show that the Earth is never flat. Hence, when next you come in contact with a flat Earther, try as much as possible not to argue blindly with them. Instead, point out concentrated scientific evidence to make them change their mind about the shape of our planet.

Note that some chronic flat Earthers will never believe you no matter the amount of evidence you reveal to them. But you still have to try your best to educate a flat Earther with these points.

Looking At The Horizon

The horizon is the line that demarcates the Earth from the sky. There are generally two major types of horizons and they include Earth-sky horizons and celestial horizons. The Earth-sky horizons are sub-categorized into local horizon, geographic horizon, and sea-level horizon. When an object moves away from you, it will start to appear smaller and slowly vanish from your sight.

However, before they finally disappear, their bottoms become hidden first before their tops slowly disappear. Another example of an Earth-sky horizon is how a ship vanishes on the horizon. If you have ever spotted a ship on the horizon, you will notice that it slowly leaves your sight in a similar style.

If you are walking or driving from a great distance, you will notice that the tops of tall objects such as mountains appear visible first before their bases. The reason why you notice all these differences on the horizon is because of Earth’s curvature.

Visible Earth Curvatures from High Altitudes

If you have ever traveled in high altitudes, you must have spotted the Earth’s curvatures. Pilots have seen this great view several times during their flights. Capt. Albert Stevens of the U.S. Army Air Corps revealed a clear image of Earth’s curvatures from high altitudes in the 1930s.

When the Capt. was flying at an altitude of 21,000 feet (6400 meters) above Villa Mercedes, Argentina in December 1930, he looked westward and captured a photo of the Earth’s curvature. This great image made the world become more interested in seeing Earth from above.

“The Andes Mountains, 287 miles [462 kilometers] away, and although taller than the plane’s altitude, lay below the sensible horizon, marked by the white horizontal line in the photograph,” NASA officials wrote in a description of the flight. “The Earth’s curvature explains this phenomenon, as described in the diagram accompanying the photograph. The Earth’s curvature is also visible laterally in the photograph, although the effect is subtle as the image encompasses only 1/360 of the Earth’s circumference.”

After the first historic image of Earth’s curvature from high altitude, Stevens and Capt. Orvil Anderson captured a photo from a balloon that lifted off from Rapid City, South Dakota in November 1935. During that attempt, they moved the balloon to a maximum altitude of 72,395 feet (22,066 m) to get the best view.

“The photograph showed the troposphere-stratosphere boundary and the actual curvature of the Earth and demonstrated the potential for long-range reconnaissance from high-altitude balloons,” NASA officials wrote.

Look Up At The Stars

If you are still having doubts looking at the horizon, you can look up to the stars to get more evidence. An article published by astrophysicist Paul M. Sutter in revealed that different stars are visible in different regions of our planet in two unique ways. The first visible way is the division between the northern and southern hemispheres.

Hence, skywatchers can clearly see Polaris, the star that remains nearly directly above Earth’s north geographic pole and is easily more visible in northern latitudes. However, as you move towards the south, heading towards the equator, Polaris will begin to disappear lower and lower towards the horizon.

Immediately you exceed the northern boundary, you will not see the star again. This is because the Earth’s curvature blocked the star in that direction. Also, when you move toward the south, you will be able to spot new constellations waiting to welcome you. However, you cannot see these new constellations in the north as the curve of Earth will obscure your view. You will also be able to see more stars from the mountaintop than you will see in the plain region.

Circular Celestial Bodies Everywhere

If you look around our solar system, you will realize that most celestial bodies have circular shapes. Without a telescope or binoculars, you can clearly see that the sun and the moon both have circular shapes. With telescopes and binoculars, you can observe the other terrestrial planets (Mercury, Venus, and Mars), gas giants (Jupiter and Saturn), and ice giants (Uranus and Neptune) and discover that they all have circular shapes.

It should remind you that our planet cannot have a flat shape while its neighboring planets have a circular shape. Keep in mind that after our Sun formed around 4.6 billion years ago, Earth about other planets in the solar system began to form 100 million years later. These planets and moons formed from the remaining nebulae materials that formed the sun. Scientists have discovered that they all formed following similar patterns.

Gravity is the reason why celestial bodies are round. Gravity pulls the space rocks together equally from all sides during the formation process. It also pulls from the center to the edge like the spokes of a bicycle wheel. This scientific interaction makes the overall shapes of planets, and other celestial bodies to be spherical. A sphere means that planets have a shape that is like a three-dimensional circle.

Lunar Eclipse

You can also see the shape of Earth during a lunar eclipse when Earth passes between the sun and the moon. This astronomical event makes the Earth cast its shadow on the moon which can be visible from Earth. The shadow of our planet is always a circle at all times of the eclipse.

This implies that no matter where you are on the planet, you can see the circular shape of our planet on the moon during the eclipse. Because the Earth is a globe, that is why it can cast a circular shadow on the moon whenever it passes between the Sun and its nearest celestial neighbor.

Photos Taken from Astronauts from Different Countries You can show a flat earther

A Spherical Earth (Image Credit: NASA)

Astronauts from different countries have visited space on several space missions. They often take photos of Earth from space during their missions in space. These images reveal the true shape of our planet from space. Even some of our robotic spacecraft capture mind-blowing images of Earth from space. You can use these images to convince flat Earthers to change their thoughts about our planet.

What Scientists Think About Debating a Flat Earther

Most flat Earthers believe in conspiracies of our planet being flat. They even think that scientists are lying to them. However, with hundreds of proofs showing our Earth is not flat, many flat earthers are yet to trust scientists. But our researchers will never give up on finding more convincing evidence to make people who believe in flat Earth conspiracies rethink.

“I don’t think this discussion is really about the actual evidence or the scientific process, however,” astrophysicist Paul M. Sutter wrote in an article published in “People who believe that Earth is flat aren’t coming to that conclusion from the same types of observations. Instead, they believe that we are being misled and lied to, that scientists (including me) want you to believe that Earth is round, despite its flatness.”

“So the question isn’t ‘Why do people believe in a flat Earth?’ but rather ‘Why do people believe in a conspiracy?’ And the answer is the same reason it always is: a lack of trust,” he added.


Despite our technological advancement and how far we have explored space, many people still believe in the flat Earth conspiracies. The claim that the Earth is flat has shown the extent people are expressing their distrust in modern science and our scientists as well. However, if you ever argue with a flat Earther, you should focus on convincing the person to trust our scientists and science in general. For additional resources, you can check out this explainer from Arizona State University. Also, check out these books to learn more about Earth and the Universe.

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