How did Columbus find out the world is round?

Answer 1

He didn't. Educated people in Europe had believed that the world was round-a sphere, spherical-for more than 1,500 years before Columbus was born.

Columbus set out to prove that a ship could reach Asia by sailing west from Europe. He believed that the world was only about 12,000 miles (19,300 km) around at the equator when most people believed, correctly, that it was about 24,000 miles (38,600 km) around at the equator. In 1488, four years before Columbus' (in)famous first voyage to the New World, some Portugese explorers had found some islands relatively far out in the Atlantic and he might've thought that they sounded like they were Asian for some reason. Spain wanted to destroy all its neighbors, so when some guy came up to them and said, "I can get you all sorts of money for guns by sailing west to India as long as I get a cut," they thought, "Eh, worst that'll happen is this guy'll get eaten by his crew before they start eating each other and the last one alive dies of starvation instead of horrible, horrible, zombie murder and we'll be out a couple boats."

When Columbus hit the Bahamas, he thought he was in India. That's why the aboriginal people of the Americas are wrongly called Indians.

Note that even if most people at the time thought that the world was flat and you'd fall off if you sailed to far, Columbus' journey woulndn't've disproved that unless he was actually in India. By the time of his death in 1506, people had already figured out that he wasn't in any known region of the world. If they thought the world was flat, all that Columbus would've proved to them is that there were another continent on their flat world. The idea of Columbus "proving" that the world is round doesn't stand up to scrutiny.

Another guy, named Magellan, later sailed all the way around the world going only west, thereby strongly suggesting that the world was round, but this still wouldn't prove the world was a sphere. It could be a half-sphere or a cylinder or anything. There's a lot of geometry and astronomy that goes into proving that the earth is spherical, both of which the ancient Greeks were good enough at in the 3rd century BCE to prove that the earth was a sphere and estimate its equatorial circumference within a few hundred miles.

Answer 2

he sailed all the way round and didn't fall of the edge. he showed that the rumours of falling off were wrong.

Answer 3

because some people would fall off if the world was flat

Answer 4

he sailed across the world to see if he would fall. if he fell than the world would be flat.