How Do We Know The Earth Isn’t Flat?

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Satellites and astronauts have provided us with sumptuous pictures of Earth’s blue curvaceous body. The surface does appear flat when viewed from the top of a mountain, but this is due to refraction. The overarching dome is clearly visible from the summit of an exorbitantly tall structure such as the Burj Khalifa.

The Matrix in The Matrix is a splendid metaphor for the Internet – a metropolitan city replete with dreary buildings where each floor consists of an interminable row of white-doored rooms. When I walk the corridors on one of those floors and randomly open a door, I find a group of people either laughing, marveling or violently flinging burnt chairs and lamps across the room while emphatically quarreling. I close that door furtively and continue walking.

One such argument that may occur in one of those rooms is the ever-famous, ineradicable Flat Earth argument. While ambling through the floors of my own domain, I opened a door to find someone fiercely arguing that all our website posts are fictional, malicious conspiracies that aim to “conceal the truth” and how he and his coterie are “waking up every day”. Strangely, a couple of times, he also asked me to fornicate and travel at the same time. Fazed by the futility of online arguments, I usually refrain, but this time I choose not to close the door. This time, I decided to settle it once and for all.

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The Flat Earth

The most optimal way to determine whether our planet is a thick disk or a huge sphere is to view it from a more distant perspective. One such picture would be enough to falsify the one hundred proofs assembled by William Carpenter in his book One Hundred Proofs that the Earth is Not a Globe. Satellites and astronauts have provided us with sumptuous pictures of Earth’s blue curvaceous body, but apparently, these pictures are “doctored”. The technology to tinge and skew does exist and can be quite easily afforded by multi-billion-dollar government-funded organizations. So, fair enough. Or as basketball player Kyrie Irving puts it: “They lie to us.”

apollo 17 photo of earth from moon
Two birds, one stone. (Photo Credit: NASA)

According to Flat Earthers or the Flat Earth Society, Earth is like a phonograph record that doesn’t rotate. The north pole lies at the center of this disk, while the South pole doesn’t exist. What is found “south” is a 150-foot tall wall of ice that forms the thick rim of this disk. No one has ever crossed this wall because NASA prohibits such “infringement”. Wait, it gets worse. Now, because the disk doesn’t rotate, days and nights are caused by the sun and moon revolving around it in a 24-hour cycle. And if the return of this barbaric, solipsistic notion wasn’t enough, when you thought it couldn’t get even worse, they believe that the diameter of the two celestial bodies is merely 32 miles.

flat earth
The Flat Earth. Image Source: Wikipedia

One word: Ridiculous. Even a six-year-old can discern Earth’s sphericity and rotation without leaving the planet’s sturdy surface. Here’s how.

Also Read: Is Earth A Perfect Sphere?

How Do We Know The Earth Is A Sphere?

Evidence that hinted at a curved Earth was gathered more than 2,000 years ago. Around 250 B.C., a few Greeks realized it with just two sticks. They fixed two sticks on the Earth’s surface 500 miles apart from each other. If the Earth was flat, the Greeks would have observed that both sticks cast no shadow when the Sun was directly above them. However, what they observed was that the stick located 500 miles towards the north did cast a shadow! It’s a no-brainer that this is possible if and only if the Earth’s surface is curved such that the other stick is “inclined”. In fact, they used the angle at which the shadow inclined to calculate Earth’s circumference with only a 10% error – an extremely impressive result, considering that it was just 250 B.C. Two sticks, that’s all it takes.

Earth curve stadia alexandria syene circumference sun rays

Another reason to change teams, which will also require some tedious traveling, is to scrutinize the stars. The earliest Greek documents cited the variation in the position of polar stars as evidence for a spherical Earth. The variation was particularly drastic between Greek settlements around the Mediterranean Sea. If the Earth were flat, the map of stars should appear the same regardless of your location, except that it doesn’t. A meticulous investigation would tell you that the night skies in the two hemispheres are undoubtedly different.

Even Aristotle, the prized student of Plato and the most brilliant logician of antiquity, observed that “there are stars in Egypt and Cyprus that are not seen in northerly regions.” But could the Earth be a cube with six sides facing six different directions? Not really. Aristotle also observed that the shadow Earth casts on the moon during a lunar eclipse is shaped like an arc. It is then Clark-Kent-is-Superman obvious that such a shape can only be witnessed when the illuminated object is curved, more precisely, a sphere.flat earth meme

Still, empiricists reasonably complain that they cannot “feel” or “see” this curvature. The surface does appear flat when viewed from the top of a mountain. What’s more, the popular ‘marker’ experiment corroborated their doubts. The Bedford Level experiment was one of the first experiments that “proved” Earth’s flatness. It was conducted in 1838 by Samuel Rowbotham along the 6-mile length of the Old Bedford river. The river is perfect for the experiment because it is uninterruptedly straight throughout its entire 6-mile length.

If you erect two markers at either end of this canal, because the Earth is curved, while peering from the line-of-sight of one marker towards the other through a telescope, you can observe that the two markers are not level with each other. However, Samuel observed that the distanced marker was aligned perfectly, despite being 6 miles apart, slightly beyond the Earth’s curvature. This is compelling evidence for a flat Earth, but what Samuel didn’t incorporate and what other Flat-Earthers deliberately ignore are the effects of refraction. Refraction bends the light reflected by the marker beyond the curve to make it appear level. Refraction is why we observe “advanced” sunrises and “delayed” sunsets.

Sunset diagram

On the other hand, perhaps people can’t “see” the curvature because they simply haven’t climbed high enough. The overarching dome is clearly visible from the summit of an exorbitantly tall structure such as the Burj Khalifa. Seriously, ask Tom Cruise. In fact, you can witness it without risking your life: send a balloon towards the blue sky with a camera attached to it and it will do the job for you, provided the violent gusts don’t impair it or NASA spies solely devoted to confiscating such nosy balloons don’t interfere and distort the footage in mid-air. Also, if all the other planets in our Solar System are pudgy and round, why should Earth be an exception?

Dubai - View from the Burj Khalifa - Downtown Dubai - The Dubai Mall - Business Bay
The curve. (Photo Credit: giggel / Wikimedia Commons)

Also Read: How Did People Figure Out That The Earth Was Round Without Any Technology?

Debunking Other Arguments

When British cricketer ‘Freddie’ Flintoff was asked why he believes the Earth is flat and doesn’t rotate, he, like any conspiracist, rather than responding with a coherent argument, retorted with an ingenious question that could make your beliefs precarious. Flintoff asked: “If you’re in a helicopter and you hover, why does the Earth not come to you if it’s round? Why, if we’re hurtling through space, would water stay still? Why is it not wobbling?”

Hmm, a very good question (although he also suggested “all governments now have bases on the South Pole.”). We have already answered the first question in detail. You can find it here. However, let me answer it in short. The reason why Earth doesn’t “pass” beneath when a helicopter is stationary over it is the same reason why a ball dropped from the top of a tower doesn’t land “behind” the spot you’d expect.

Coin fliping from top of building

If you were to jump inside a plane whizzing at 500 mph, you’d still land on the same spot. The plane doesn’t gallop ahead when you are mid-hop because you and the plane exist in the same frame of reference. Similarly, the Earth and everything it encompasses exists in the same frame of reference. Every object is essentially rotating and revolving at the same speed as Earth. This means that you and the oceans and the air in which the helicopter lays dormant, are rotating at 460 meters per second!

According to Newton’s first law, things remain as they are until acted upon by an external force. The ball would deviate, you would land on a different spot, the ocean would wobble, and the Earth might pass beneath you if the frame of reference — the plane or the Earth — experiences an acceleration or deceleration. For instance, if a celestial body were to collide with Earth with the exact force that would bring its rotation to a halt, we and the oceans would be thrown off the ground immediately, like the passengers of a fast-moving car would when it abruptly collides with something.

The Earth would pass underneath and a helicopter hovering above the U.S. could then land on Australia, if the helicopter happened to be loitering outside the planet in space. However, to simply describe the expenses to achieve this as “highly uneconomical” would be an understatement.

Earth atmosphere from space
The Earth would pass underneath and a helicopter hovering above the U.S. could then land on Australia, if the helicopter were loitering outside the planet in space. Photo Credit: studio023 / Shutterstock

Furthermore, it is unclear why gallons of water and a Sun rotating around like a carousel should be glued to a still, flat Earth, unless Flat-Earthers have renounced the principles of gravity as well.

Now, geodesy, a branch of mathematics that deals with the shape and area of Earth, has determined with the help of satellites, Earth’s size and shape with unprecedented accuracy to within a centimeter. We have found that the Earth is not a perfect sphere, but an oblate spheroid, a sphere bulged around the center and slightly flat around the poles, due to the combinatorial effects of gravity and the force of the planet’s rotation.

I give up. (Photo Credit: NASA)

Cynicism is the most dangerous and despicable of prisons, for it is often impossible to escape. It is cynicism that fuels the distrust of Awakenedsoul95, Truthseeker21 and Wakeupsheeple666 in the sincerity of science. It is also cynicism that spurs my distrust when I’m sure they cannot be convinced, when I’m sure they are incorrigible. If facts won’t change their minds, then what will? Isn’t the plush-red Sun or a hooting ship sinking into the horizon and reappearing when viewed from higher ground convincing?

If our fortuitous consciousness has one benefit, it is the ability to distinguish callous, unprejudiced fact from congenial, snug belief. As science communicators, perhaps as conscious human beings, it is our duty and moral obligation to spread truth, despite how abhorrent it may be. Yes, the Earth isn’t flat, and neither are powerful politicians shape-shifting lizards. Just deal with it.

Also Read: If Earth Were Flat, Would You Fall Off The Edge And Into Space?

References (click to expand)
  1. Indiana University Bloomington -
  2. What Would Happen if the Earth Were Actually Flat?. Columbia University
  3. (8) The Round Earth and Christopher Columbus - NASA.
About the Author

Akash Peshin is an Electronic Engineer from the University of Mumbai, India and a science writer at ScienceABC. Enamored with science ever since discovering a picture book about Saturn at the age of 7, he believes that what fundamentally fuels this passion is his curiosity and appetite for wonder.

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