![]() During the Age of Exploration, European sailors noticed that, as they sailed south, "new" constellations came into view-stars that could never be seen from their home latitudes. By measuring the size of this angle, and knowing the distance between the two cities, Eratosthenes was able to calculate the Earth's diameter, coming up with a value within about 15 percent of the modern figure.Īnd when Columbus set sail from Spain in 1492, the question wasn't "Would he fall off the edge of the world?"-educated people knew the Earth was round-but rather, how long a westward voyage from Europe to Asia would take, and whether any new continents might be found along the way. ![]() If the Earth were flat, that would be impossible: The Sun would have to be the same height in the sky for observers everywhere, at each moment in time. But in Alexandria, in northern Egypt, on that same day at the same time, Eratosthenes had observed the Sun being several degrees away from overhead. In the 2nd century BCE, a thinker named Eratosthenes read that on a certain day, the people of Syene, in southern Egypt, reported seeing the Sun directly overhead at noon. The ancient Greeks also knew Earth's size, which they determined using the Earth's shape. What we observe during lunar eclipses is that the planet's shadow is always round, so its shape has to be spherical. We know the Earth is spinning, so it can't present one side toward the Sun time after time. And if the light fell at an oblique angle, the shadow would be a football–shaped ellipse. But if light hit the disk edge-on, the shadow would be a thin, straight line. If sunlight just happened to hit the disk face-on, it would have a round shadow. (Why no one has ever seen this supposed wall, let alone crashed into it, remains unexplained.) Wouldn't a disk-shaped Earth also cast a round shadow? Well, it would depend on the orientation of the disk. Some flat-Earth believers claim the world is shaped like a disk, perhaps with a wall of ice along the outer rim. The ancient Greeks figured out that Earth was a sphere 2300 years ago by observing the planet's curved shadow during a lunar eclipse, when the Earth passes between the Sun and the Moon. The difference is tiny-just one-third of 1 percent. The Earth has been spinning since it was formed, and "if you have a spinning fluid, it will bulge out due to centrifugal forces." You can see evidence for this at the equator, where the Earth's diameter is 7926 miles-27 miles larger than at the poles (7899 miles). "Over a long time-scale, the Earth acts like a highly viscous fluid," says Surendra Adhikari, a geophysicist at the Jet Propulsion Laboratory in Pasadena, California. Today the Earth is mostly solid with a liquid outer core, but when the planet was forming, some 4.5 billion years ago, it was very hot and behaved like more like a fluid-and was subject to the squishing effects of gravity.Īnd yet, the Earth isn't a perfect sphere it bulges slightly at the equator. That's not the case with any other shape-some part of the material will be more than 5 inches from the center of the mass. No part of the mass is more than 5 inches from the center. Say, for example, you have a sphere of modeling clay that is exactly 10 inches in diameter. All of that pulling makes an object as compact as it can be, and nothing is more compact than a sphere. These objects, and billions of others, have the same shape because of gravity, which pulls everything toward everything else. Not every celestial body is a sphere, but round objects are common in the universe: In addition to Earth and all other known large planets, stars and bigger moons are also ball-shaped. To say the evidence is overwhelming is an understatement. There is zero doubt about this fact in the real, round world. "Theories" abound on YouTube, and the flat-Earth Facebook page has some 194,000 followers. Hughes isn't alone in his misguided belief: Remarkably, thousands of years after the ancient Greeks proved our planet is a sphere, the flat-Earth movement seems to be gaining momentum. For the cost of his rocket stunt ($20,000), Hughes could have easily flown around the world on a commercial airliner at 35,000 feet. He fell back to Earth with minor injuries after reaching 1875 feet-not even as high as the tip of One World Trade Center. ![]() According to The Washington Post, Hughes thought they were "merely paid actors performing in front of a computer-generated image of a round globe." It didn't matter that astronauts like John Glenn and Neil Armstrong had been to space and verified that the Earth is round Hughes didn't believe them. The plan: Strap himself to a homemade steam-powered rocket and launch 52 miles into sky above California’s Mojave Desert, where he'd see Earth's shape with his own eyes. On March 24, 2018, flat-earther Mike Hughes set out prove that the Earth is shaped like a Frisbee.
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