I am not sure what the heck is going on here. Humanity seems to be going off the rails. First, we elect an incoherently rambling, narcissistic, racist, sex offending, billionaire conman as president, now YouTube is being inundated with “Flat Earthers,” people so shameless in their ignorance, that they not only admit to believing in, but argue that the Earth is a flat disc! I could never have imagined that anyone, other than a small child or possibly a Middle Eastern goat herder, could be this ignorant. Honestly, stupid is the only way to describe it. If this is where we are today, it disturbs me to think what the future holds for our species. How far back are we going to go? Might we be seeing blood sacrifices to bring back the buffalo? At this point anything is possible.
Now, I don’t know what kind of mind can wrap itself around the notion that the Earth is flat, and that every scientist, pilot, astronaut, cosmonaut, navigator, sailor, geographer and anyone with any common sense is lying to them. To be fair, this may be the result of some conspiratorial mental disorder. Perhaps, where these people live, there’s too much lead in the water (welcome to Trump’s anti-EPA America).
Science is the very best tool we have for knowing what is true and what is not. It’s the reason we can sit in a house, with a fridge full of food, and stare at a computer screen making YouTube videos. Using the scientific method, we make inferences about the nature of the world based on our observations. If you look outside your window and see a tree, you can be certain that tree is there. These observations, properly measured and recorded, is what is collectively referred to as evidence. But what Flat Earthers fail to understand, or refuse to understand, is that they must take into account all of the evidence. Going back to our tree analogy, if I were to walk outside to discover a lawn company had parked their truck in my driveway with a realistic picture of a tree on it, I might conclude that the tree I thought I had seen was, in fact, a photograph. The evidence presented by Flat Earthers in their videos is what is called “selective evidence.” They focus on the tree without ever going outside. Using this technique, I could prove anything I wanted. A scientific theory, to be taken seriously, must take into account all of the evidence. If there is even one piece of evidence that discredits your theory, your theory is wrong. And the only theory we have about the shape of the Earth that satisfies all of the evidence is the spherical theory.
What is this evidence, you ask? I’ve made a small list below. If Flat Earthers fail to explain any one of these things, then their argument is invalid, and that’s putting it kindly.
1. All astronomical bodies we can see with the naked eye are spherical: the moon, planets, the sun and stars.

2. The sun rises and sets. If the Earth were flat, the sun would shrink, and we would not have day or night.
3. You can see the shadow of the Earth on the moon during a lunar eclipse and at certain phases. The only shape that always produces a round shadow is a sphere.
4. Stars rotate around us. If the Earth were a flat disc, we would see the stars growing more distant, and they would never entirely move beyond our line of sight. If the stars are dipping under a disc-shaped Earth, you would have to explain why people on the other side of the world can still see them.
5. Certain stars can only be seen in the northern or southern hemispheres. Try calling someone in Australia. Ask them to take a photo of the night sky. Their stars are different. This is only possible on a spherical Earth.
6. Time zones are only possible on a spherical Earth. On a flat Earth, daylight would last the same amount of time everywhere.
7. In Scandinavia, night can last for 22 hours. This only makes sense on a spherical Earth.
8. It’s colder toward the poles, the further north or south you travel. Conversely, it tends to get warmer as you move closer to the equator. This only makes sense on a spherical Earth, as less sunlight reaches the upper or lower regions where the Earth curves away from the sun.
9. GPS can only work on a spherical Earth.
10. Satellite TV can only work on a spherical Earth. You can observe satellites with a store bought telescope, and you can see the International Space Station with the naked eye.
11. We have countless photos of a spherical Earth. It is statistically impossible to fake all of the photographic evidence, and commit tens-of-thousands of scientists who have worked for NASA, the European, Indian and Chinese space agencies, and private space agencies, to a world-wide conspiracy. Not to mention we have amateur astronomers who make the same observations on their own. It would also cost more to hide the truth than to simply go into space!
12. Ships at sea vanish from bottom to top. This is only possible on a spherical Earth. Don’t believe some crackpot’s YouTube videos. Go out to sea! Witness it for yourself!
13. You can see much further from a higher altitude. This only makes sense on a spherical Earth. Conversely, it is impossible to see things in the opposite hemisphere, whereas on a flat disc you should be able to see the Himalayas with the naked eye, or at the very least, with a telescope.
14. Airlines navigate using a spherical Earth model, which is why you can fly faster from New York to London, than say, from New York to Paris.
15. A flat Earth is not physically possible. Gravity pulls things equally in all directions, which is why every major astronomical body is spherical. If the Earth were flat, it would collapse back into a sphere.
16. You can see the Earth is a sphere from a high altitude or by simply looking out at sea. This is why the Ancient Greeks and Egyptians knew the Earth was a sphere. In fact, the Greeks correctly calculated the circumference of the Earth using nothing but two sticks and trigonometry. I have seen the curve of the Earth myself and you can too. Stand atop a high altitude overlooking the sea and turn your head from side to side. You can also use a straight ruler and line it up to the horizon.