The turning point in the realization that the Earth has the shape of a ball is considered to be the beginning of the Age of Discovery, when Christopher Columbus discovered America in 1492. but it has long been no secret to modern science that Columbus was not the first European to set foot on the American continent. Long before the end of the 15th century, the Vikings visited America.
But could it be that before the 15th century people not only assumed the spherical shape of the Earth, but were also sure that their world was round? For those who are familiar with ancient scientists, it will not be a discovery that Pythagoras is one of the most famous and authoritative philosophers of Ancient Greece, the opinion that was listened to by the majority of the inhabitants - back in the 6th century BC. believed in the spherical shape of the earth.
Some ancient scientists even tried to calculate the circumference of the planet. The most famous of these was the Greek mathematician Erastothenes (276 BC - 194 BC), who calculated the circumference of the planet as the length of 252,000 stadia. In those days, there were no generally accepted units for measuring distance, so the scientist had to take the stadiums where sports competitions were held as a basis. Surprisingly, Erastofen carried out extremely accurate calculations for his time. Depending on which type of stadium - Egyptian or Greek - he used in his calculations, the accuracy of the data obtained is from 16% to 1%!
So, already in the 5th century BC, and probably in more ancient times (we do not forget about the strong astronomical schools of Babylon and Egypt), people knew that the Earth was spherical. And the beginning of the era of the Great geographical discoveries convinced the most recent skeptics of this. The opinion that the ancient people considered the Earth to be flat was probably formed under the influence of the mythology of many peoples, especially ancient Greek, where the action takes place in a flat world.