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8 Reasons We Know the Earth Isn’t Flat

8 Reasons We Know the Earth Isn’t Flat

Rappers with improperly punctuated names aside, most of the human population is pretty sure the Earth is round. Neil deGrasse Tyson doesn’t have to take to Twitter to confirm it (or drop a counter-diss track, though he absolutely should), because every kind of investigation that we can do shows that the blue marble we live on is indeed marble-shaped.

Here are 8 ways we know the Earth is round, and some you can prove yourself!

You Don’t Weigh Less at the Horizon

While flat-earthers will contend that there is no such thing as gravity, this force unites the entire universe. It’s everything from what makes the numbers jump on a bathroom scale to the reason why planets and stars form. It uniformly pulls everyone on the surface of Earth toward our planet’s center of mass (roughly the exact center). That’s why you’ll weigh the same in Los Angeles as you will in Jakarta.

If the Earth was flat, gravity would no longer pull everyone the same way. If the flat Earth would be something like a disk, those at the edge of the disk would be pulled relatively sideways, while those at the center of the plate would be pulled straight down. The difference would change your weight enough to confuse a bathroom scale. Considering that humans have been to every landmass on Earth without celebrating sudden lightness, we can rule out a flat planet.

You Don’t Fall Off The Planet

Where is the edge of the world according to flat-earthers? The answer changes, but it usually involves some impenetrable barrier at said edge that prevents people from going past or falling off. Global conspiracies apparently prevent people from investigating these boundaries.

But in reality, humans have circumnavigated the planet in planes and ships, and no one has fallen into space. Rather, when ships traveling large distances on the ocean do appear and disappear on the horizon, they do so either mast or hull-first, respectively. If the Earth was flat, and you had the right optics, you could watch a ship sail from New York to Africa without losing sight of it. You can’t because the curve of the Earth makes the ship dip below the horizon.

You Don’t Always See the Same Constellations

Hit up a friend in Australia and ask them what constellations they can see at night. Now tell them which ones pepper your patch of darkness. They won’t be the same. Because the Earth is a shape other than a flat disk, when looking into the night sky the Earth itself can block your view.

If the flat Earth theory were true, everyone should be able to see the same constellations all the time, as if we all were staring up from the same section of summer grass.

We’ve Seen Earth From Space, From Multiple Angles


This is “Earthrise,” arguably the most famous photo ever taken. It was beamed back to us by the astronauts on the Apollo 8 mission on Christmas Eve, 1968. It shows the Earth as a perfect (from that vantage point at least) azure orb speckled with land and clouds, and us. It’s true that the Earth could be a disk in this photo, and the astronauts were seeing it face-on, making it appear spherical.

However, since 1968, we’ve used our spacecraft and satellites to take literally thousands of photos of Earth, and from every angle. Each shot shows Earth like Earthrise did. That’s only possible if Earth is a disk in three dimensions — a sphere. Today, astronauts like Scott Kelly even show us the curve of the Earth in real-time. He sees a sunrise every 90 minutes, a phenomenon impossible with a disk.

The Same Objects Make Different Shadows

Here’s one you can try at home. If the Earth were flat, you could drive two sticks into the ground at any place on Earth, and the shadows those sticks would make would be the same length. (Because the Sun is so far away from Earth, its incoming rays can be considered parallel).

Place a stick in the ground on a sunny day, then measure the length of the shadow. At the same time, call a friend who is at least a few miles away from you and tell them to do the same. The lengths you measure will be different! The curvature of a spherical Earth means that sun rays will hit each stick differently if they are far enough apart.


Measuring shadows like that is how Greek astronomer Eratosthenes very nearly calculated the exact circumference of the Earth in…250 B.C. Yep. We’ve been certain the Earth is round since maybe 500 B.C., or 2500 years before a rapper dropped a flat Earth diss track.

Timezones Exist

To make the seasons work with a flat Earth, advocates claim that the Sun orbits in a circle above our disk, like a tetherball on an invisible string. But timezones exist. Try calling someone in China right now and convincing them that you are experiencing the same time of day (and then apologize).

A flat Earth can’t account for how some parts of the planet are provably in darkness while other parts are bathed in light.

The Rest of the Solar System

Like how we’ve seen the Earth from many angles and found it round, we’ve sent cameras to the rest of the planets in our solar system and snapped photos of them from many angles too. They all appear to be spheres. That makes sense if gravity is the main force in the universe pulling cosmic gas and dust and rock together to form planets.

The chances that the Earth is the only planet in the solar system that is non-spherical, yet subject to the same forces as other planets, are zero.

Eclipses Show You Earth’s Shape

Have you ever seen a lunar eclipse? It’s when the Earth passes in between the Sun and our moon and casts a shadow over the lunar surface. If you look closely, you can pick out a slight curvature.


Curvature is possible with a flat disk, but even flat-earthers admit that the Earth spins. If the Earth were flat, there would be some people that occasionally see a straight line projected on the moon (the edge of a disk). That hasn’t happened since humans looked up, so a sphere is the logical shape to assume.

So sorry, B.o.B, the Earth is not flat. From what we know of the universe, it can’t be. A conspiracy could never be big enough to deny us our planet’s true shape. We live on a pale blue dot, believe it or not. A dot from every angle makes a sphere, who you been listening to, this is what you should hear. That sh**t comes straight from Carl Sagan, flat Earth make no sense, my head be aching. The only thing flat is your flow, tell me B.o.B, why does Earth have timezones? You know what, forget it, I’m done moving my lips. Get back to me when you explain an eclipse. [Editors Nots: mic drop]


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