A Flat Earth?

A 10-minute video summarizes this article: tinyurl.com/AFlatEarthModel

A one-hour physics colloquium based on this article.

50-minuta versio tinyurl.com/PlataTero, kun partopreno de Derek Roff.

In the US and in Britain there are organized groups of people who strongly believe that the Earth is flat. The US group is named “Flat Earth International” and it holds regular conferences (https://flatearthconference.com). A major website for the US flat-earth movement is http://flatearth101.com and that of the UK movement is https://wiki.tfes.org. It is claimed that there is a massive conspiracy to hide the fact that the Earth is flat, with all governments and all scientists working together to maintain the fiction that the Earth is round. This conspiracy, if real, would include most scientists, philosophers, and religious leaders on several continents, going back more than two thousand years. This belief could be considered harmless, but the movement provides additional fuel for the notion that all scientists are conspiratorial liars and are not to be trusted, which is a dangerous notion with serious consequences for society.

There have been many attempts by scientists to rebut the flat-earth notions, but often the counter-arguments are not well chosen. For example, since flat-earthers believe that the Sun is only a few thousand miles away, it’s not useful to start a counter-argument with “Since we know that the Sun is nearly 100 million miles away…” The flat-earthers put great emphasis on naked-eye observations, so here I will emphasize the fact that their own model makes predictions that are wildly different from naked-eye observations.

A popular model of the US flat-earthers’ version of the truth is that the Earth is a stationary flat circular disk (with local hills and valleys) with the North Pole at the center and an impenetrable wall of ice at the edge where, in some accounts, armed guards prevent one from crossing. The Sun and Moon are said to be spotlights circling the disk at a constant height of about 3500 miles and with diameters of about 30 miles. These numbers make the angular size of the Sun and Moon be one-half degree, as is observed in the real world at all times (but only at noon at the equator in the flat-earth world). These numbers also attempt to account for the different angular heights above the horizon of the Sun and Moon seen at different latitudes. A rotating dome above the disk carries spots of light (not distant “stars”) that move in circles around the North Star. (Here is a computer model of the UK flat-earth model.)

Many flat-earthers believe that there is no such thing as gravitational forces between objects, the proof being that if you place a ping-pong ball in contact with the bottom of a suspended bowling ball, the ping-pong ball falls, so evidently the bowling ball does not exert a gravitational force on the ping-pong ball to prevent it from falling. If you don’t believe there is such a thing as gravity, then Australians can’t be suspended upside-down, and this is taken as additional evidence that the Earth can’t be round (that is, very nearly spherical; actually an oblate spheroid). All the evidence in favor of a round Earth and a huge Universe around the Earth is thought to have been faked, including all of the videos and photos released by NASA and the space programs of all other countries.

The starting premise of all this is that you should believe your own eyes rather than what some authorities claim. This attitude can be seen as positive, since direct observation is a necessary foundation for science and understanding. However, the way that this plays out among flat-earthers has some very serious limitations. The believers generally do not make many careful observations, usually preferring to quote flat-earth authorities. The believers do not make the necessary deductions from the fact that their own flat-earth model makes predictions of naked-eye phenomena that are utterly different from what one actually sees. At the very least this should have triggered attempts to improve the flat-earth model.

Secondly, they fail to understand that progress in science has included the need to invent and deploy ever more sensitive technologies to go beyond what can be understood solely from naked-eye observations. Examples of the latter point abound. No unaided human eye has seen a virus or an atom; we had to invent microscopes of increasing capability to augment human vision. We can’t see the electromagnetic waves that carry conversations to our cell phones, but those waves are very real and are obviously detectable by a cell phone. In 1798 Cavendish was the first to construct an apparatus sufficiently sensitive to be able to measure the extremely small gravitational forces that two large metal balls exert on each other, and the measurements were in agreement with the vastly larger gravitational force that the entire massive Earth exerts on these balls.

Of course the strongest evidence for a flat Earth is that it looks flat (again, ignoring local variations in the form of hills and valleys). The Earth is so large that an initially horizontal beam of light will be only 8 inches (20 cm) higher above the surface after going a mile (1.6 km), and for a distance of N miles, the difference is N-squared times bigger. This is a somewhat difficult measurement to make, and for large distances an object can seem to be raised or lowered by mirage-like bending of light due to atmospheric conditions near the surface. Though such measurements have been made (over water) that verify that the Earth is round, these results are rejected by flat-earthers. At the end of the recent documentary on the flat-earth community, “Behind the Curve,” some flat-earthers repeat the experiment themselves and are stunned that the results are not consistent with a flat Earth, but this seems to have had no impact on the community. Also near the end of the documentary one hears a flat-earther saying that, using a complex device called a ring laser gyroscope, his measurements showed that the Earth does in fact rotate, “but don’t tell anyone.”

There is an unresolvable tension in this community between claiming to be scientific by providing a model that will agree with naked-eye observations, and the need to reject disproof of this model for the sake of maintaining a congenial community that delights in sharing knowledge of a vast conspiracy and feeling the satisfaction of disproving conventional science.

I wrote a Web VPython program (webvpython.org) to create a navigable computational version of what seems to be the most popular US flat-earth version (it differs in some important ways from the UK flat-earth version). It is to the credit of the flat-earth community that their model of a flat Earth is sufficiently well described as to make it possible for me to create a computer model.

In the section below on “Using the computer model,” which includes a link to the program, you can explore this model yourself. While roaming around in this 3D visualization of the flat Earth, it was easy to identify several predictions of the flat-earthers’ model that disagree dramatically with what one actually sees with the naked eye:

1) The flat-earth model predicts that the visual diameter of the flat-earth Sun can, depending on your latitude, vary by more than a factor of 2 between noon and sunrise or sunset, which we do not observe. At sunrise or sunset the flat-earth Sun is much farther away from an observer than at noon, so it would look much larger at noon (and the sunlight would be over four times as intense at noon), whereas in reality the Sun is so very far away that its tiny change in angular size from sunrise to noon is undetectable. Also, the angular size of the flat-earth Sun is very different when viewed from different latitudes, which is not what is observed in the real world.

2) The flat-earth model predicts that the flat-earth Sun will never get anywhere near the horizon, despite the fact that we see sunrises and sunsets with the Sun at and even sinking below the horizon. Because the flat-earth Sun is about 3500 miles above the disk, an observer on such a flat Earth should always see lots of sky between the horizon and the Sun; at sunrise and sunset the flat-earth Sun is far above the horizon.

3) A closely related naked-eye observation is that at sunset one sometimes sees the bottoms of low-lying clouds lit by the setting Sun. The flat-earth model predicts that this cannot happen, since the flat-earth Sun is about 3500 miles above the Earth.

4) The flat-earth model predicts that the North Star will be visible even from Argentina, despite the fact that it is not visible from anywhere a few miles south of the equator (the North Star is a small angular distance from the point around which it seems to circle, so that at a short distance south of the equator you can see it some of the time). In fact, from the edge of the flat-earth disk, the North Star will be about 25 degrees above the northern horizon. Similarly the flat-earth model predicts that the angular height of the North Star should be about 60 degrees in Dallas Texas, but it’s actually only 33 degrees above the horizon, which is a huge naked-eye discrepancy. The latitude of Dallas is 33 degrees, and on a round Earth one predicts that the North Star will be 33 degrees above the horizon, as is observed.

5) The flat-earth model predicts that if you watch a constellation that is near the eastern horizon at nightfall, it will grow larger until midnight, as it comes closer to you, then smaller as it moves away from you toward the west. No such effect is in fact observed. Closely related is the prediction that as you move farther from the North Pole, the larger will be constellations in their closest approach to you. Moreover, in all cases the brightness of the flat-earth stars and flat-earth Sun will vary depending on how close or far you are from them, which is not observed in naked-eye observations. This implies that the stars and Sun are very far away, so that moving large distances on the Earth’s surface hardly changes the large distance to stars and the Sun. Also, except at the North Pole, a constellation in reality never moves parallel to the horizon during the night as it does in the flat-earth model.

There is no room for the well-known southern-hemisphere constellation, the Southern Cross! Just as the North Star should be well above the horizon even in Argentina, so should all the constellations of the southern hemisphere be well above the horizon in the US. Not only do we not see these constellations in the US, there isn’t room for all the southern-hemisphere constellations and all the northern-hemisphere constellations to be jammed into the single hemisphere that is the rotating flat-earth dome.

6) If you move away from the North Pole you’ll see that the tracks of the stars around the North Star are no longer circles but are now ellipses, which does not agree with long-exposure photos of the night sky such as, oddly, this photo displayed on a page of the major US flat-earth site (scroll the page to find the image): http://flatearth101.com/fact-vs-theory

Note too that if you are at the equator of our real world, and you see a star rise straight east of you, that star continues up to the zenith and then down to set in the west, whereas in the flat-earth model the stars are on the rotating dome and move parallel to the horizon; they can’t move perpendicular to the horizon.

Incidentally, that flat-earther’s page contains a major error, namely the claim that “the North Pole Star is situated perfectly over the North Pole center of earth and never moves a single inch night after night year after year century after century.” If you use Ctrl-+ to blow up the image, you will see what is well known to amateur astronomers, namely that Polaris is not “situated perfectly over the North Pole” and leaves a trail just like all the other stars. Moreover, with the centuries, which star is closest to being above the North Pole changes, due to the “precession of the equinoxes,” the name given to the visual effects that are due to the fact that the axis of the spinning Earth “precesses” like that of a gyroscope. This effect is due to torques exerted by the Sun and Moon on the Earth.

The commonality of these effects is that you don’t need any special equipment in order to make the relevant observations. It’s true that if you want to make the North Star disappear you will have to travel to a little bit south of the equator. As an alternative, check with trusted friends who live south of the equator and can look for the North Star on your behalf. Or just compare the angular height of the North Star above the horizon at your location, and notice that it dramatically contradicts the angle predicted by the flat earth model. There are many other problematic aspects of the flat-earth model that can be tested with some precision equipment, although these are still accessible to anyone who wants to make an investment of time and money. For example, amateurs as well as scientists have verified the earth’s curvature using long-baseline surveying over water or have measured the gravitational forces that ordinary-sized objects exert on each other, as Cavendish did.

The key point is that if the Sun and stars are only a few thousand miles away from an observer as predicted by the flat-earth model, their individual sizes and their distances from each other on the sky, and their brightness, will necessarily change as they move a few thousand miles toward or away from the observer during the day and night. In contrast, if the Sun and stars are very far away compared to the size of the Earth, then changes in their distances from the observer during the day and night will be such a small fraction of those distances that naked-eye observations will not detect any changes, and that is precisely what we actually observe.

The flat-earthers take pride in having created an alternative model of the Earth and its surroundings. However, they have not taken the critical next step, a crucial step in a scientific approach, which is to take their own model seriously. This would mean checking whether the predictions of the model are consistent with observations, including, at the very least, naked-eye observations.

Some History

In her 2007 book “Flat Earth: The History of an Infamous Idea,” Christine Garwood documents that while early Babylonian and Egyptian cosmology included a flat Earth, the Greeks realized that it had to be round. Aristotle traveled south in Egypt, saw that he could see constellations that were new to him and couldn’t see some familiar constellations, and correctly concluded that the Earth is not flat. A century later Eratosthenes measured with remarkable accuracy the radius of the Earth by comparing the lengths of shadows of vertical rods in two Egyptian cities on the same longitude, at the same time of day. Garwood points out that from that time forward until the mid-1800s, everyone in the West accepted that the Earth was round.

Eratosthenes’s measurements could be interpreted to determine either the 4000-mile radius of a round Earth or the 4000-mile height of the Sun above a flat Earth, as can be seen in the following diagram. Presumably it was at least in part Aristotles’s analysis that led Eratosthenes to choose the round-earth interpretation. Another reason for rejecting the flat-earth interpretation could have been the fact that the apparent size of the Sun doesn’t change during the day, despite the changing distance that the flat-earth model requires.

Eratosthenes measurement

Garwood comments that there is a persistent myth that at the time of Columbus, people thought the Earth was flat, but that is not true. Columbus incorrectly believed that the Earth was much smaller than people of his day knew it to be, and he thought it was small enough that his provisions would support his ship voyage from Spain to China. He was way off and would have starved if he hadn’t run into the islands of the Caribbean. Galileo’s heresy wasn’t a claim that the Earth was round; it was stating that the round Earth, accepted by the Catholic Church, wasn’t at the center of the Universe.

As documented by Garwood, in England in the mid-1800s there arose a challenge to the Earth being round instead of flat, and the contemporary flat-earth societies in the UK and the US are inheritors of that movement. She shows that the main motivation was discomfort with secularism in general and with evolution in particular. One of the arguments used by flat-earthers was to find passages in the Bible that could be interpreted as support for a flat Earth. It is probably not a coincidence that the flat-earth movement started in England, where modern geology can be said to have gotten its start, stimulated by the search for minerals in the context of the industrial revolution. The geologists showed that the Earth must be much older than 6000 years, and they uncovered fossils of animals that were completely unknown.

It is relevant that on the first page of the important US flat-earth website, http://flatEarth101.com, there is this statement: “The majority of people believe they are descendants of monkeys living on a giant spinning ball of water hurtling and spiraling through space. All of which was not created but was formed billions of years ago in some outrageous cosmic explosion that created everything from nothing. If this were true it would mean we are insignificant pieces of cosmic dust! We aren’t special in the least, without a purpose in being here. Our self-worth and outlook on others and the world as a whole is warped. Well, the exact opposite is true, we are special and are not some random result of a billion year old explosion!”

There is a larger context for all of this. In her 2000 book “The Battle for God: Fundamentalism in Judaism, Christianity and Islam” by Karen Armstrong, a distinguished scholar of religion, Armstrong shows that although fundamentalists in all of the three major monotheisms think of themselves as returning to ancient tradition, in fact all three fundamentalisms are quite recent phenomena. She makes a distinction between “logos” (the word; logic and rationalism) and “mythos” (the stories we tell; the only language we have for discussing some kinds of important experiences). Both of these forms of discourse are essential to being human. Fundamentalists saw the growing power of science, logos par excellence, and in reaction wanted their own form of logos. They came to claim for their holy books, works par excellence of mythos, the status of logos. Instead of celebrating the story-telling mythos of the holy books, many fundamentalists are literalists for whom these books have the same logos-based characteristics as scientific works. Of course not all flat-earthers are fundamentalists, but there has been and continues to be a significant connection. It is noteworthy that in a speech at a recent flat-earth conference, there was much applause every time the speaker cited the Bible as proving the Earth is flat.

Members of the flat-earth movement emphasize how much value they place in the friendships and other social aspects of belonging to a community. It is a common human trait to value social connections, and to accept the common beliefs of ones’ chosen peers. Social connections insulate and protect flat-earth belief from the impact of the many discrepancies and observable errors in the flat-earth model. In spite of the rhetoric concerning direct observation and scientific reasoning, the flat-earth movement is ultimately not based on logos, but on mythos.


I owe a large debt to Lee McIntyre, a philosopher of science who became interested in the flat-earth movement as an example of science denial and, in an editorial in the September 2019 issue of the American Journal of Physics, asked for help from physicists on how to rebut the arguments of flat-earthers. I strongly recommend his excellent 2019 book, “The Scientific Attitude: Defending Science from Denial, Fraud, and Pseudoscience.” I also owe much to the thoughtful insights and suggestions of my friend Derek Roff. After completing this work I found a 2019 book by J. W. Braun, “The Flat Earth Fallacy & The Globe Earth Proof,” which puts a similar emphasis on naked-eye observations that strongly disagree with the predictions of the US flat-earth model. I recommend Sabine Hossenfelder’s video on flat-earthism: https://youtu.be/f8DQSM-b2cc. Here is a transcript of her video: https://backreaction.blogspot.com/2020/08/flat-earth-science-wrong-but-not-stupid.html 

Using the computer model

Click tinyurl.com/FEmodel to start up the computer program in a separate browser tab, and drag that tab out of the browser so that you can see this text and the computer display at the same time. You don’t need to install any software; the Web VPython program runs in your browser.

You should see a transparent rotating dome with embedded stars and their long-exposure trails. The dome sits on a stationary flat disk that represents the flat Earth.

Position the mouse just above the center of the scene and press the mouse button to move forward into the flat-earth model. Release the mouse button to stop moving. As you get closer you will see radial longitude lines and circular latitude lines drawn on the green flat Earth. The yellow line lies between your original position and the North Pole at the center of the disk. A red circle marks the equator. You can’t move farther into the model than the east-west light blue line that is perpendicular to the entry yellow line. You can roam backwards with the mouse below the center of the scene, and you can roam left or right with the mouse to the left or right of the center of the scene.

If you click “Look around,” roaming is disabled and you can use the mouse to look in any direction without moving. This is useful for inspecting the model. Look up and you’ll see the stars with their circular trails centered on the white North Star (Polaris). Look about halfway up to find the moving yellow flat-earth Sun that moves in a circle about 3500 miles above the equator, this being a day near the spring or autumn equinox. When this Sun moves beyond the cyan-colored east-west line its color is dimmed to gray to indicate that you are now in darkness. Sunrise for you occurs when the Sun crosses the eastern end of the east-west line, and sunset occurs when the Sun crosses the western end.

1) The changing size of the Sun: Click “Follow Sun”, and the camera will constantly look at the yellow Sun, placing it in the middle of the scene. You might start by observing from the equator, where the Sun at noon has the observed angular width of half a degree. Watch for “sunrise” in the east (when the Sun becomes bright) and click “Pause”. Observe the size of the distant Sun. Click “Run” and then click “Pause” when the Sun is overhead. Note that it looks significantly bigger now, because it is significantly closer to you. Or simply let the model run and watch the “Sun width” degree display below the scene, which is the angular width of the Sun at this moment as seen from where you stand. Move to a different latitude (note the numerical latitude indicator below the scene), and you’ll see that the angular size of the flat-earth Sun changes, because you are closer or farther from it, and this effect is not what is actually observed. The size of the Sun is exaggerated to make it easier to observe it, but the “Sun width” display is the computed angular width for the flat-earth model.

2) The Sun never gets near the horizon: As you watch the Sun move around the Earth, note that it never gets close to the horizon, because it is high above the flat Earth.

3) Cloud illumination: Imagine low-lying clouds, which are very far below the Sun. Since the flat-earth Sun is very high above these clouds, even at sunset it cannot illuminate the underside of the clouds. Yet it is not uncommon at sunset to see the bottoms of low-lying clouds illuminated by sunlight.

4) Angular height of the North Star: In “Roam” mode, navigate to a latitude of 33 degrees (like Dallas, Texas) and in “Look around” mode observe the viewing angle for the North Star by looking toward it. You’ll find that it’s about 60 degrees above the horizon, but in Dallas the North Star is in fact only 33 degrees above the horizon, as is predicted and observed on a round Earth, for Dallas’s location of 33 degrees north latitude.

5) The changing size of constellations: Near the horizon are 12 identical triangular “constellations.” Roam to the equator, click “Look around”, and click “Pause”. Now look around at the various constellations, and of course those nearest to you are bigger than those farther away. Or click “Run” and watch the constellations grow in size as they move from the east to the west. Or, click “Pause” and roam toward one of the “constellations,” noting that it gets bigger and bigger, but in the real world the apparent size of a constellation doesn’t change with latitude. Also, note that the constellations move parallel to the horizon, which is not observed in the real world except at the North or South Pole.

6) If you move far from the North Pole and then look at the North Star in “Look around” mode, you’ll see that the tracks of the stars around the North Star are no longer circles but are now ellipses, which does not agree with long-exposure photos.

All of these effects shown in the computer model ought to be visible with simple naked-eye observations of the sky if the Earth is flat. However, what we actually observe when we look at the sky is very different from what the flat-earth model predicts, as demonstrated by the computer model.

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47 Responses to A Flat Earth?

  1. Tom K says:

    Are you sure that this is what the Flat Earth model predicts? You linked us to the model at tfes.org which describes how the celestial model works. https://wiki.tfes.org/Sunrise_and_Sunset

  2. BruceSherwood says:

    The key point is, as I said, “A popular model of the US flat-earthers’ version of the truth is that the Earth is a stationary flat circular disk….” It is this US version that I have attempted to model, not the UK version discussed at wiki.tfes.org. I realize that there is tension between the US and UK movements. I have not studied the UK model in detail, nor tried to make a navigable 3D computational model.

  3. Trent says:

    What measurements of curvature over water are you referring to in paragraph 7?

  4. BruceSherwood says:

    I know of two such measurements. One is documented in Garwood’s history, along a canal in England in the 1800s, at the beginning of the flat-earth movement. The other is the one, which is mentioned in my article, done by surprised flat-earthers as described at the end of the documentary “Behind the curve”. Less formally, there are the experiences of sailors for centuries of seeing the peaks of distant mountains and the tops of distant ships before seeing the whole mountain or ship upon getting closer. However, as I comment in my article, there can be some ambiguities in these observations, because it is well known that temperature inversions and their converse can affect long-distance observations, seeming to raise or lower distant objects, as in the case of a mirage. This problem is particularly serious for observations along a line of sight that lies near the ground. For that reason I think that more conclusive naked-eye observations are those involving the Sun and stars, as I’ve discussed.

    • (Dr) David Fisher says:

      R.T.Gould (Oddities) mentioned the case of a 19th-century Caribbean island-dweller who knew when sailing-ships were arriving perhaps days before they were visible. I did not believe this until I read (perhaps in AJP) of a freakish optical phenomenon in which optical paths can follow the Earth’s curve due to temperature gradients. I shall have to go through my voluminous files to check.
      On a serious note: the general fake-news and pseudoscience upticks are currently paralleled by an increase in the number of totalitarian leaders worldwide. Such leaders have a habit of backing crackpot theories: e.g. Lysenkoism in the USSR, the cultural revolution in China and the lesser-known anti-technology movement in Franco’s Spain. One can well imagine Trump adopting flat-Earth theory if it suited his purposes! Who would stop him?

      • BruceSherwood says:

        Yes, I feel the over-water evidence, though in fact very strong, is susceptible to reasonable-sounding counterarguments, whereas I don’t see how to get around the fact that the sizes of the Sun and Moon and constellations don’t change, nor that the angular height of the Pole Star is wildly different from what a flat Earth predicts. Good point about authoritarian attacks on science (one might also cite religious attacks on science as being authoritarian). I thought I knew a lot about Franco’s Spain (I speak Spanish and have read many novels in Spanish about that period), but I’m unaware of “the lesser-known anti-technology movement”. Say more?

        • (Dr) David Fisher says:

          It is difficult to make any sort of impression on these people, given the background of general public ignorance concerning all things scientific. ‘General public’ unfortunately also includes journalists and other ‘opinion-formers’. A UK chat-show host recently expressed belief in the ‘G5 spreads Covid’ nonsense and a UK journalist (interviewing an ‘astronaut’) asked him if he had brought back any Moon-dust: he had been only to the space-station (of course)! I also question the apparent technical knowledge of quiz-show stars: how much of that knowledge is rote-learned? It is odd that those who know a little about a lot earn titles like ‘mastermind’ , while anybody who knows ‘too much’ is called a nerd … or is suspected of being autistic. I surprisingly forgot to mention the Nazis and Welteislehre in my list of ‘despots backing crackpots’. I shall try to find the academic paper which I downloaded concerning Franco. The problem is that I have about 25000 downloaded papers and they are listed only by author and page-number. Keyword searches can take a long time. Briefly, Franco wanted to return Spain to some sort of agrarian fantasy-land. It is all the more shocking that he called upon Nazi technology to help him.

        • (Dr) David Fisher says:

          PS: I have found the paper (P.Preston, Science and Society, 68[3] 2004, 277), but now find that I have misrepresented the contents. It was not Franco’s idea, but that of some of his generals … such as Mola,. “His use of aircraft of the Luftwaffe revealed much of his attitude to the war and its purpose. He was obsessed with the total annihilation of Spanish industry as a prelude to building a “clean” agrarian Spain. This is clear from his spinechilling comments at the time. On April 2, 1937, he clashed with the commander of the Condor Legion, General Sperrle. Mola wanted Sperrle to destroy Basque industry, reasoning that ‘Spain is dominated in a totally sick way by the industries
          of Catalonia and the Basque Country. For Spain to be made healthy, they have to be destroyed.’
          So this was not really a pseudoscientific theory; just part of a vicious class war. I formally remove it from my list of examples.

  5. BruceSherwood says:

    I found a description of another, recent experiment involving viewing of distant objects over water:


  6. Larry says:

    I agree with Tom’s comment from last year: it would be great to somehow incorporate this new wrinkle the FETs have introduced, which is electromagnetism bending light rays so the sun and moon appear to rise and set. (Actually not sure how new it is, since they don’t date the articles on tfes.org.)

    Walter Bislins has a flat earth model that tries to show the necessary degree of light bending to make it appear that the sun and moon are rising and setting on a flat earth. He intended this to show how wildly off the flat earth model is, but some FETs seem to have taken it as a serious model of reality. http://walter.bislins.ch/bloge/index.asp?page=flat+earth+dome+model

    • BruceSherwood says:

      Thanks for the link, which I’ve added to my article. I don’t see how to add the UK model as an option in my own model. I have come to think that the most powerful evidence, also highlighted by Bislins, is that when everything is nearby, you automatically get huge differences between naked-eye observations and the predictions of either flat-earth model.

  7. Larry says:

    Thanks for your work on this!

  8. Roberto Terlevich says:

    Thanks for the simulation and discussion, a nice idea.

    In the text you mention the word horizon eight times, I would like to raise the point that in the flat earth scenario there is no horizon as from anywhere on a two dimensional flat surface an observer, whose head is above the surface, should be able to see all the surface up to the assumed edge, i.e. the antarctic ice wall. In other words, the flat earth has an edge or limit but no horizon.

    Thus the mere fact that there is a horizon clearly visible from any beach as a thin sharp division between the water and the sky, is a strong prove of the curvature of the earth.

    • BruceSherwood says:

      I guess it’s a failure of the imagination, but I’m not able to conceive of any visible difference between the two situations. Why won’t I see see “a sharp division between the water and the sky” with a flat ocean? Is the distinction that the edge of the flat earth is thousands of miles away and therefore won’t look like a “sharp division”, whereas the horizon from a height of 2 m is quite close?

      • Roberto Terlevich says:

        OK, let’s be more specific.

        The surface of a flat ocean should be visible all the way up to the position of an obstacle (i.e. “non-ocean”) in the line of sight. The flat earth map (centered in the north pole) indicates that looking southwest from the west coast of Ireland the first obstacles will be the Caribbean islands and the north coast of South America (Venezuela, Surinam, Brazil). Looking a bit further to the east, the Antarctic wall should be visible with the Cape Verde islands projected in front. Further east the Canary islands and the west coast of Africa. Adding a bit of atmospheric scattering will diffuse the view but not completely obstruct it. We know this is the case because in a clear day is possible to see the Sun and Moon raise and set behind the horizon even when they are at least at ~4000 miles distance, according to the flat earth scenario.


        — The separation between a flat ocean and the sky is composed of “obstacles” in every direction.

        — A flat ocean cannot produce the sharp and rapidly changing wavy horizon that we see. The horizon is a direct consequence of the curvature.

        • BruceSherwood says:

          Thanks! That helps. I’ll mention that one often points to the experience of sailors seeing mountains grow when approaching land, and I realize that I’ve seen this effect when driving west across the US prairie: first one sees just the top tips of the Rocky Mountains, and slowly one sees more and more as you get closer. Perhaps I should add some mountains to my computer simulation?

          • BruceSherwood says:

            Another thought: The rising pale Moon is visible only because, being on a round Earth, we’re looking through not much atmosphere. If we were looking through 4000 miles or more of atmosphere we might not be able to see the rising Moon, or it would at the least be much distorted.

  9. D.E. Buckner says:

    Hi Bruce,

    I just watched your video https://www.youtube.com/watch?v=2HrWi5Hp0rk all the way through. It was excellent, and your point (and Lee’s point) about the importance of reaching out is well taken.

    Thanks also for introducing me to FE101. This page http://www.flatearth101.com/flight-map-on-flat-earth with the 1942 map is very funny if you look carefully.



  10. BruceSherwood says:

    Glad you liked this. What’s funny about the map? If the flat-earthers think this map proves their thesis, they haven’t paid attention to the map-maker’s explanation of how distorted the map is….

    • Anton S. says:

      The funny thing about the FE page cited by Ed Buckner may be that it reproduces a chart showing that distances (along latitude lines) are not preserved in the polar equidistant map.

      Related to that page, I recently saw a video collecting several examples of intercontinental flights that made emergency landings far to the north of a straight line on, say, a Mercator map – demonstrating that a polar equidistant map is not too bad a distortion of the northern world.

  11. Mike Ketterman says:

    I will bookmark this, it answers a lot of questions that I have thought about. I won’t get caught off guard again when somebody out of the blue says “you believe NASA?” Although my first thought was do I believe 165,000 people, some I went to school with are all lying?
    Anyway. Question.. am I correct to say that every model I’ve seen for the flat earth there can never be a full moon in New Zealand at night?

    • BruceSherwood says:

      At least in the flat-earth of the US movement, I don’t see any reason why there can’t be a full moon in New Zealand. Their moon is a floodlamp moving above the disk, presumably with the option to fill a circle either fully or partially. Why do you think there couldn’t be a full moon in their model?

      • Mike Ketterman says:

        I saw a mechanical model a while back, not a spotlight, the sun and moon both rotating over a flat earth. The moon, to be full at night, the sun had to be close to the outside edge to light the side of the moon facing southern continents. And of course it would have to be daytime on those continents.
        I’m not sure how their system works, I already know a system that works and it doesn’t need a magical thing in the sky or extremely advanced creatures make it work, like a spotlight.

  12. Steve Newbery says:

    One other aspect of the FE model that doesn’t match reality is that in winter the sun is circling above the Tropic of Cancer, while in summer it’s circling abobe the Tropic of Caprocorn. This means that in winter it has to be moving much faster, around 2000mph compared to 1200mph in summer.

    However, at the equator the day and night are a constant 12 hours all year long, and the distance of the arc covered by the sun across the sky is the same too – it has to be if the day length remains the same.

    So this appears to be a fundamental problem. If the sun is moving much faster, over the same distance, the day in winter would have to be much shorter. But of course it is not.

    • BruceSherwood says:

      Good points. As you’ve seen, I chose to talk about an equinox to avoid the additional complications of dealing with seasonal issues.

  13. MikeinSonoma says:

    If the earth was flat and around earth is a hoax, wouldn’t ships captains and air pilots, need to have two sets of navigational books? One book to navigate by on the flat earth and one for a around earth to deceive people?
    There’s a location on the West Coast when flying to a location in Australia you fly over Hawaii islands, according to a global earth. The same route on a flat or if you would not go anywhere near Hawaii. On a global earth if you fly from the North Pole to the equator maker right turn fly the same distance make a right turn you end up where you started. On a flat earth you would have to make three returns to end up in the same spot.
    So all somebody would have to do is get on the one of the ships or planes and take there sets of navigation books to show the world… So silly.

    • Anton S. says:

      I like to imagine the day in engineering school when students are told, “Now that you have spent years learning to parrot the Round Earth Hoax line fluently for the masses, it’s time to throw away all that you’ve learned – forget about ‘gravity’, that’s part of the hoax – and start over with the Flat Earth truth.”

      Flatties sometimes brandish documents, often from NASA, whose front page contains a line like “The formulae herein assume a stationary flat earth.” Exceptio probat regulam in casibus non exceptis.

  14. BruceSherwood says:

    Indeed; good examples. I believe it is the case that surveyors in seemingly flat Illinois have to make corrections at the one-mile level to take into account the fact that the land is not in fact flat.

    Another example that gets mentioned is that the flat-earthers claim that the distance from Australia to Argentina is an extremely long distance, and that this is the reason why there are no such flights available. When it was pointed out that there are such commercial flights the flat-earthers refused to believe this and/or claimed that the passengers are drugged so that they don’t realize how very long the flight was.

    • Anton S. says:

      Okay but why are there no direct flights between, say, Santiago and Perth? Because they’d hit the Wall of Ice!

      Much of the United States is surveyed in one-mile squares, with offsets due to the changing length of a latitude line – which would be true in either world; someone with time on their hands could examine these offsets to see which fits better.

      • BruceSherwood says:

        Good points.

      • Anton S. says:

        Santiago and Perth? I don’t know what I was thinking.

        • MikeinSonoma says:

          There’s an app called FlightTradar24, it’s a live flight tracking app. I use it to track family when they’re flying. You can track flights from south America to Australia.
          I just checked there was one flying from South Africa to Australia. It takes a nice dip toward Antarctica and back up again. You can actually be on the plane with Internet service and track yourself. You can see the land islands you’re flying over. It’s just getting harder and harder for the flat earthers to deceive themselves.

  15. Hello Bruce,

    Your blog is an excellent resource, and this post in particular is great.

    One more very simple observation that rules out the flat-Earth model that you discuss: In the Northern Hemisphere, stars move in counter-clockwise arcs during each night, whereas in the Southern Hemisphere, stars move in clockwise arcs during each night. It should be simple enough to verify this, just by going outside on a clear night every half hour and observing, and then asking a friend in the opposite hemisphere to do the same, and then compare notes.

    • BruceSherwood says:

      That doesn’t sound right to me. I live in Portland Oregon in the U.S., at 45 degrees north latitude. At night if I look to the north, the stars go counterclockwise, but if I look to the south, the stars go clockwise. This will be true no matter what latitude I’m at, because the common element is that no matter where I am, stars rise in the east and set in the west.

      • MikeinSonoma says:

        There isn’t a star located over the southern pole, it’s just a coincidence that there is one above the north pole, but there still is a spot in the southern sky that all the starts rotate around. From the perspective of the southern hemisphere, they rotate clockwise, opposite of the north’s perspective that is counterclockwise. I’m in Northern California, when I look south, the stars more or less follow the horizon (Yes, in a clockwise direction, east to west). If I lived on the equator, I wouldn’t see any full circles, just stars rising in the east and arching and setting in the west.
        A flat earth would only have ONE pivot point (Up or north counterclockwise), a globe Earth has TWO.(Up North counterclockwise and down South clockwise) I don’t know why this isn’t talked about more, it is a major issue, if not killer, for the flat earth idea.

  16. You are right, and I am wrong. Let me try to say what I meant correctly this time:

    If you are in the Northern Hemisphere and take a series of photographs of stars, with the “fixed point” (North Celestial Pole) in the photographs, you will see a bunch of arcs, with stellar motion along the arcs in the CCW sense.

    If you are in the Southern Hemisphere and take a series of photographs of stars, with the “fixed point” (South Celestial Pole) in the photographs, you will see a bunch of arcs, with stellar motion along the arcs in the CW sense.

    The photographs are not necessary, making observations in the general direction of your hemisphere’s “fixed point” suffices.

    In the flat earth model you discuss, observers in both hemispheres will observe stars moving along CCW arcs. There is only one “fixed point” in the flat-Earth model, the “upper” celestial pole, if we decide to call it that.

    This is such a simple observation, that anyone can do, and requires no measurements with specialized equipment, so anyone should be able to falsify the flat-Earth model, with the collaboration of a friend in the opposite hemisphere.

    • BruceSherwood says:

      To me, the more compelling issue is that in the flat Earth world there is, as you say, only one fixed point (Polaris), and it would be visible even in Argentina, which is very much not the case.

    • MikeinSonoma says:

      Santo, excellent point… And I really did just post mine before reading yours, we are of the same mind.

      • Santo D'Agostino says:

        Thanks, Mike. Your comment, and the host’s, about the existence of two fixed points being a killer for flat-earth models, is on point.

  17. Bob Bobby says:

    My favorite part is that the author created his own model of what the opposition “think” and then debunked that. Also, literally no proofs of the satantic global theory, only debunks based on model created by the author. Classic.

  18. Mackie says:

    I was discussing this with my child. We came up with two queries about the flat Earth model, which we’ve not seen answers to.
    1. How could the sun appear circular at all times of day, if in fact it’s some sort of spotlight illuminating a circular region of a (flat) Earth? Surely it would, by necessity, look oval, except when directly above one?
    2. Where does all the solar energy come from? We’re not convinced a small spotlight sun rather close to us could run on fusion power. Maybe it runs on batteries?

    • Bruce says:

      Good points. Yes, their spotlight ought to look elliptical when not directly overhead. Same problem as with the motion of the stars around Polaris. I’ve never seen any description of the energy source for their Sun. Maybe in the flat earth world it doesn’t need any energy source? For that matter, there isn’t an energy source for the “points of light” that are pinned to their rotating dome. I’m delighted that you were able to include your child in this story.

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