Flat-Earthers are a strange bunch, let’s face it. When they aren’t supporting their theories by claiming the world works like Pac-Man or launching themselves from homemade rockets to the edge of space, they’re generally conducting nonsense experiments such as taking a spirit level on a plane to prove the Earth is flat. (Spoiler alert: He doesn’t prove what he thinks he proved).

Fortunately, to counteract the flat-Earthers, along with the endless pictures of Earth from space, we have many simple ways to pull apart their arguments.

One man’s experiment has gone viral on Reddit this week after he looked at one of the most popular claims by flat-Earthers: That a flat-looking horizon somehow proves the Earth is flat.

Flat-Earthers regularly point out that when you look at the distance, the horizon looks pretty flat.

Greg Pagel looked at this in a widely-seen post on Reddit. For the post, he looked at the horizon on the coast where he grew up.

Using Google Maps, he found the distance between two pieces of land on the edges of his photograph, which turned out to be 13.5 kilometers (8.4 miles). Doing some quick math, he figured out that given the Earth is (approximately) 24,140 kilometers (25,000 miles) in circumference, you should see an arc of around 0.12 degrees on a horizon of 13.5 kilometers (8.4 miles).

Now, a 90-degree arc you’d notice immediately, as he points out.

But once you’ve gone down to 1-degree arcs, it starts to be a whole lot less noticeable.

And by the time you look at a 0.12-degree arc, it’s impossible to see the curve at all.

Essentially, as people have been telling flat-Earthers for years, the horizon looks flat because the Earth is gigantic in scale, not a goddamn baseball. If you’re viewing a horizon and you know the distance between two points, you can do the experiment for yourself using Greg’s equations in his full Imgur post or in his YouTube video.

Although, as people have been quick to point out:

“I think he proved the Earth was round when he mentioned Google Earth, which takes pictures of Earth, ya know from a satellite…in space…”

Alternatively, you can prove the Earth is round for yourself just by looking out to sea and finding a boat. You can see, if it’s distant enough, it appears below the horizon.

This wouldn’t happen if the world was flat – you would be able to see the boat clearly on the horizon. Unless you caught the boat during the precise moment it fell off the edge of the Earth, of course, which nobody in the history of our species ever has.

Or use any of these methods described here.

[H/T: The Independent]