[TotesNotReptilian]

For your consideration, I present two simple proofs that the earth isn't flat. The beauty of these proofs is that they are easy for anyone to verify without expensive equipment or expert knowledge. No faith in NASA/government/scientists required.


The sun sets below the horizon, maintaining its size and shape.

According to most flat-earthers, the sun is a spotlight, rotating in a plane 3000 miles above the earth. Let's make some predictions based on this model:

• The sun should decrease in size as it rotates away from us in the afternoon.

Doesn't happen. The sun stays approximately the same size.

• The sun should not go below 20 degrees from the horizon (based on 3000 miles distance from earth, and 8000 mile diameter of the equator).

It definitely goes below 20 degrees. In fact, it sinks all the way below 0 degrees. In fact, it is possible to see the sun halfway below the horizon, halfway above the horizon, which should absolutely never be possible.

• The sun should appear to always curve north as it travels across the sky. (The point about which it rotates)

This generally happens in the northern hemisphere! Horray! Unfortunately, near the equator, the sun travels in a straight line due west. Bummer. Significantly south of the equator, the sun even curves to the south. Double bummer.

• If the sun is a flat disc, it should appear elliptical as it travels away from us.

Doesn't happen. The sun stays perfectly round.


The existence of the South Celestial Pole

When we are in the Northern Hemisphere, the stars appear to rotate around some point in the North. This is consistent with both a flat earth and spherical earth. Excellent.

When we are near the Equator, the stars appear to travel due west. Again, this is completely consistent with a spherical earth, but on a flat earth, we would expect the stars to still curve north. What gives?

As we continue moving into the Southern Hemisphere, the point in the North about which the stars rotate sets below the horizon, and another point about which the stars rotate rises in the South. The farther south we go, the higher this "South Celestial Pole" rises in the sky. Again, this is completely consistent with a spherical earth, but completely unexplainable on a flat earth.

Some people mention "Celestial Gears" as an explanation for this phenomenon, but I have never seen it actually described. Until there is at least a slightly plausible model explaining the existence of this phenomenon, it is solid evidence against the flat earth model.


Both of these proofs are easy to verify for yourself. The first requires simple observation of the sun on a clear day, preferably near the ocean so that mountains don't obstruct your view. The second only requires travelling to the Southern Hemisphere (unless you already live there) and observing the stars.

[Luke 22:35-38]

Nice. Now watche as the flat earthers squirm, dodge, ignore, insult, and call it irrevelant.

[rabinoz]

For your consideration, I present two simple proofs that the earth isn't flat. The beauty of these proofs is that they are easy for anyone to verify without expensive equipment or expert knowledge. No faith in NASA/government/scientists required.


The sun sets below the horizon, maintaining its size and shape.

According to most flat-earthers, the sun is a spotlight, rotating in a plane 3000 miles above the earth. Let's make some predictions based on this model:

• The sun should decrease in size as it rotates away from us in the afternoon.

Doesn't happen. The sun stays approximately the same size.

• The sun should not go below 20 degrees from the horizon (based on 3000 miles distance from earth, and 8000 mile diameter of the equator).

It definitely goes below 20 degrees. In fact, it sinks all the way below 0 degrees. In fact, it is possible to see the sun halfway below the horizon, halfway above the horizon, which should absolutely never be possible.

• The sun should appear to always curve north as it travels across the sky. (The point about which it rotates)

This generally happens in the northern hemisphere! Horray! Unfortunately, near the equator, the sun travels in a straight line due west. Bummer. Significantly south of the equator, the sun even curves to the south. Double bummer.

• If the sun is a flat disc, it should appear elliptical as it travels away from us.

Doesn't happen. The sun stays perfectly round.

Sure, I agree, though I believe "the Wiki" maintains that the sun is a 32 mile sphere. Don't get me started on "spotlight sun" or not.
The FE explanations for these observations seems quite bizarre to me. Perspective, somehow makes sun seem to set behind the horizon. Magnification by the "atmoplane" keeps the sun (magically,  exactly) the same size as it moves from noon to sunset.

The existence of the South Celestial Pole

When we are in the Northern Hemisphere, the stars appear to rotate around some point in the North. This is consistent with both a flat earth and spherical earth. Excellent.

When we are near the Equator, the stars appear to travel due west. Again, this is completely consistent with a spherical earth, but on a flat earth, we would expect the stars to still curve north. What gives?

As we continue moving into the Southern Hemisphere, the point in the North about which the stars rotate sets below the horizon, and another point about which the stars rotate rises in the South. The farther south we go, the higher this "South Celestial Pole" rises in the sky. Again, this is completely consistent with a spherical earth, but completely unexplainable on a flat earth.

Some people mention "Celestial Gears" as an explanation for this phenomenon, but I have never seen it actually described. Until there is at least a slightly plausible model explaining the existence of this phenomenon, it is solid evidence against the flat earth model.


Both of these proofs are easy to verify for yourself. The first requires simple observation of the sun on a clear day, preferably near the ocean so that mountains don't obstruct your view. The second only requires travelling to the Southern Hemisphere (unless you already live there) and observing the stars.

Well, I do live in the Southern Hemisphere, so the South Celestial Pole is not mystery,but FEers never seem convinced.
The only place "gears" appear in "the Wiki" is in:

The Coriolis Effect
Wind Currents
The Wind Currents are put into gradual motion by the attraction of the Northern and Southern Celestial Systems, which are grinding against each other as gears at the equator line.

Water Currents
The rotation of small scale liquids in opposing hemispheres was debunked by Snopes.
As for water currents on a large scale; they're simply gradually put into motion by the winds. Water currents in the Northern Hemisphere will tend to rotate in one direction while currents in the Southern Hemisphere will tend to turn in another direction.

Stop laughing, or I will quote more Wiki! 

[TotesNotReptilian]

The FE explanations for these observations seems quite bizarre to me. Perspective, somehow makes sun seem to set behind the horizon. Magnification by the "atmoplane" keeps the sun (magically,  exactly) the same size as it moves from noon to sunset.

I didn't bother addressing the perspective explanation, because anyone with any amount of common sense knows that perspective can't cause two objects to appear to be behind each other when they aren't actually behind each other. If a flat-earther comes along to make that argument, I'll gladly address it. Until then, I'll assume they moved on from that silly idea... I hope.

Ditto for the magnification explanation. The picture shown in the wiki in support of the magnification argument is a line of cars with the headlights on. The headlights in front are dim compared to the headlights in back. Of course, the headlights in front aren't even facing the viewer...

Obviously lights get dimmer/smaller as they move away from you.

[geckothegeek]

One very simple proof that the earth isn't  fllat is the flat earth definition of the horizon and the distance to the horizon on a flat earth compared with reality.

[TheTruthIsOnHere]

One very simple proof that the earth isn't  fllat is the flat earth definition of the horizon and the distance to the horizon on a flat earth compared with reality.

If the horizon you describe is your eyes are actually resolving the vertical curvature of the earth, wouldn't you be able to perceive the horizontal curvature as well?

That is absolute proof that the horizon isn't the curvature of the earth, just the resolution of your eyes or whatever apparatus you're using looking into the distance, subject to the rules of perspective.

[Ecthelion]

If the horizon you describe is your eyes are actually resolving the vertical curvature of the earth, wouldn't you be able to perceive the horizontal curvature as well?

No, how would that follow? There'd be a number of prerequisites:
The human mind would have to be able, in the first place, to perceive a slight horizontal curvature
You would have to look at objects far enough away that your field of view is at least a few kilometers wide
You would have to still be able to perceive the resulting difference even at that distance

Are all these conditions actually met?

[geckothegeek]

If the horizon you describe is your eyes are actually resolving the vertical curvature of the earth, wouldn't you be able to perceive the horizontal curvature as well?

No, how would that follow? There'd be a number of prerequisites:
The human mind would have to be able, in the first place, to perceive a slight horizontal curvature
You would have to look at objects far enough away that your field of view is at least a few kilometers wide
You would have to still be able to perceive the resulting difference even at that distance

Are all these conditions actually met?

Another simple  reason the horizon is definite proof that the earth isn't flat.:
If the earth was flat the horizon would be at a great distance - where the "dome" meets the "ice wall" - and you would probably just see a blur  because of the thickness of the "atmoplane" in between.
An observer on the beach, looking out to sea or on the deck of a ship would be the best places to observe this.
But - because the earth is a globe - and there really is the curvature of the earth - what you really  see on this example is a distinct line (the horizon)  where the sea and sky meet.
And you can estimate the distance you can see to the horizon . This depends on your height above the sea. The lookout in the crow's nest can see much farther than the lookout on the bridge of the ship. If the earth was flat there would be no need for placing crow's nests or radar antennas on the highest maps on ships. Navy Manuals have charts showing the distance to the horizon for different heights.
The person on the beach can see about 3 miles to the horizon. The lookout on a crow's nest 100 feet above the sea can see about 12 miles.
If the earth was flat both could see at an infinite distance at sea on a clear ,  calm sunny day. If it wasn't for the "atmoplane " of course. And I don't know if they still make Kodak Ektachrome Infra-Red FIlm and filters and if you had a camera with a powerful enough  telescope lens and if you were at sea with nothing but the sea between you and the ice wall you could get some good pictures of the ice wall. I was in the Navy once and took a lot of pictures. Too bad I didn't think of doing that. I had the camera, lenses, film and filters to do that. I could have gotten some pictures of the ice wall for the flat earthers  to prove the earth was flat. Alas and alack ! A great opportunity I missed !

P.S. Oh sorry.......Flat earthers don't take photographs as evidence.

[rabinoz]

One very simple proof that the earth isn't  fllat is the flat earth definition of the horizon and the distance to the horizon on a flat earth compared with reality.

If the horizon you describe is your eyes are actually resolving the vertical curvature of the earth, wouldn't you be able to perceive the horizontal curvature as well?

That is absolute proof that the horizon isn't the curvature of the earth, just the resolution of your eyes or whatever apparatus you're using looking into the distance, subject to the rules of perspective.

You ask "wouldn't you be able to perceive the horizontal curvature as well?" No, not at ALL.

At any altitude the horizon will be exactly the same distance from you (the observer) whether the earth is Flat or a Globe - just think about it!

The big difference is that the "horizon" on a Flat Earth is simply caused by our vision becoming "blurred" even with a "clear air" by scattering in the atmosphere. Even if there is no dust, water droplets or any other pollutants the oxygen and nitrogen molecules of the air scatter the light. This puts an upper limit of visibility of a few hundred kilimetres, though some have reported longer distances for say high snowcapped mountains in very good conditions.

But, the big difference is that for a Globe for an observer standing near sea-level the horizon is only a few kilometers away and under clear conditions will look sharp.

Wide Spacer

As on these photographs. Note that the horizon even on the right one with 20x zoom still has a sharp sea-air horizon, but the tanks behind are getting quite hazy.

I have tried to find "convincing photos" of what I think a Flat Earth horizon might look like. The nearest I can get are photos from a high altitude such as:

Taken from Sea Level and 35,000 ft
Out of: Visually discerning the curvature of the Earth by David K. Lynch

The "theoretical" distance to horizon from 35,000 ft is about 240 miles, which is about the "Rayleigh" limit in clear air.
The blurred horizon in the distance is OK, but the photograph is taken from an altitude above most of the atmosphere, so we see the top fading into the deep blue and black of space, rather than the sky blue we see.

I tried merging the sky from the left one and the lower part from the right picture and ended up with the picture on the right. Yes, it's a "composite (fake)" picture, but is something like the way I would imagine the Flat Earth horizon to look.

Wide spacer

So to answer you question, no we do not see any significant horizontal curve, but we do very clearly see the effects of the curvature when looking towards the horizon. We see not only a sharp horizon (when the air is reasonably clear) and objects do disappear behind the "bulge" whatever excuses FEers might like to drag up about "perspective" etc!

[TotesNotReptilian]

One very simple proof that the earth isn't  fllat is the flat earth definition of the horizon and the distance to the horizon on a flat earth compared with reality.

While I agree this is good evidence against a flat earth, the reason I didn't include it is because it isn't quite as easy to set up a good experiment to verify it. For example, look at all the youtube videos claiming that horizon-distance experiments support a flat earth. Of course, almost all of them are poorly documented, use sloppy math, and don't control for refraction. But that's my point: it is easy to mess up and get the wrong conclusion.

Another simple  reason the horizon is definite proof that the earth isn't flat.:
If the earth was flat the horizon would be at a great distance - where the "dome" meets the "ice wall" - and you would probably just see a blur  because of the thickness of the "atmoplane" in between.

Again, I agree that this is evidence against a flat earth, but I would be hesitant to call it definitive. Especially since you can only guess as to how blurry the horizon would be. Without hard evidence as to what such a horizon would look like, are you surprised that it is routinely dismissed?

All your other points are good, but kind of a derailment from the original point of this thread. Of course, no flat-earthers were responding anyway, so... meh.

[BillNotNye]

I want to add to this. I hope you FE believe in how solar systems form. You know right? A giant mass of gas and dust gathered around, then the center builds up mass into the star, then that speeds up rotation and causes the particles to collide and grow. Anyways, how would a flat earth do that? How do we see the other plants in our solar system, or the tails of the Milky Way? Why is earth the only Flat thing in the universe? Look I like what you guys are doing. This is what science is about. Bending something each and every way to try and prove it wrong (even though it's already proven that earth is round) But another thing is how does the other plants stay around us? the comets, the asteroid belt, the kuipler system? Where do meteoroids come from? I hope you don't say something like "look it up yourself you filthy round earther" but I don't really have the time to search every page to find out how that works. Oh and also how about the new planet? The one bigger or the same size as Jupiter? How does that work too?

[TotesNotReptilian]

I want to add to this. I hope you FE believe in how solar systems form. You know right? A giant mass of gas and dust gathered around, then the center builds up mass into the star, then that speeds up rotation and causes the particles to collide and grow. Anyways, how would a flat earth do that? How do we see the other plants in our solar system, or the tails of the Milky Way? Why is earth the only Flat thing in the universe? Look I like what you guys are doing. This is what science is about. Bending something each and every way to try and prove it wrong (even though it's already proven that earth is round) But another thing is how does the other plants stay around us? the comets, the asteroid belt, the kuipler system? Where do meteoroids come from? I hope you don't say something like "look it up yourself you filthy round earther" but I don't really have the time to search every page to find out how that works. Oh and also how about the new planet? The one bigger or the same size as Jupiter? How does that work too?

If you are interested in flat-earthers' opinions on the formation of the solar system, start a new thread. It's an interesting question, but it isn't relevant to this thread.

[Sputnik]

One very simple proof that the earth isn't  fllat is the flat earth definition of the horizon and the distance to the horizon on a flat earth compared with reality.

If the horizon you describe is your eyes are actually resolving the vertical curvature of the earth, wouldn't you be able to perceive the horizontal curvature as well?

That is absolute proof that the horizon isn't the curvature of the earth, just the resolution of your eyes or whatever apparatus you're using looking into the distance, subject to the rules of perspective.

Standing in the middle of a circle, looking outward at its arc, you would see straight lines. You have to look at the circle from outside to recognize its curve.

[TotesNotReptilian]

Ugh, still only off topic comments, but since no flat-earthers are responding to the original topic...

If the horizon you describe is your eyes are actually resolving the vertical curvature of the earth, wouldn't you be able to perceive the horizontal curvature as well?

That is absolute proof that the horizon isn't the curvature of the earth, just the resolution of your eyes or whatever apparatus you're using looking into the distance, subject to the rules of perspective.

How about instead of guessing, you do the actual math and calculate how much curvature you should expect to see in the horizontal direction? Then you can compare your prediction with reality, and see if you correct! This would be much more convincing than just guessing.

Standing in the middle of a circle, looking outward at its arc, you would see straight lines. You have to look at the circle from outside to recognize its curve.

Your wording is kind of confusing, but I think I understand what you mean. Let me take a whack at it:

If you are standing very near the surface of the sphere, relative to the size of the sphere, the horizon will appear as a straight line. You have to look at the sphere from a significant distance away from the sphere, relative to its size, to recognize the curve of the horizon.