How did they find out the world was round,they said it was before people went into space?

Question

meaning how would they know that,before they saw the world from a distance?

Answer 1

In addition to ships sinking below the horizon, and the shape of the earth's shadow during a lunar eclipse, Eratosthenes in ancient Greece did some observations and calculating...

He knew there was a point in Egypt where the sun was directly overhead during the summer solstice. By using this as one angle, and measuring a shadow's angle in Greece on the same day, he surmised the circumference of a Great Circle through both points. His estimate for the earth's size was fairly accurate, given the limitations of his data.

Answer 2

The earliest methods were:
1) By noticing that the earth's shadow always has a round shape (when it's cast upon the moon during a lunar eclipse); and:
2) By noticing that faraway ships seem to "descend" when they're sailing away, as if they're going around a corner. If you look at an outbound ship through a telescope, you can see that its bottom part disappears first, and the top of the mast disappears last.

Columbus had little to do with it. The ancient Greeks knew that the world was round 2,000 years before Columbus' time. (This was also many centuries before telescopes, Kepler, Galileo, Copernicus, and the other people mentioned in other posts.) Columbus was simply the first guy to take practical advantage of the fact by sailing in the opposite direction from most people.

The story about measuring the lengths of shadows doesn't really count as evidence for roundness (there are other things that could account for this even on a flat earth). It is true that Eratosthenes used the lengths of shadows to measure the SIZE of the earth, but that was long after the earth was already known to be round.

Answer 3

Mostly just from looking around and thinking about what they saw. Virtually all seafaring peoples in history have understood that the Earth is round from the visible evidence of the horizon. You can actually see the curvature from the top of a ship's mast. And the horizon at sea always appears to be the same distance away. Any other shape, and that wouldn't be true.

Probably the first formal logical proofs of the spherical shape were made by Aristotle, who noted (as many travelers did) that the constellations changed their paths in the sky as you moved north or south. And the curved shadow during a lunar eclipse - but not just because it's curved. A disc-shaped Earth would also cast a curved shadow. But it would usually elliptical - not circular - depending on the "height" of the moon. Only a sphere would always cast a circular shadow.

Eratosthenes calculated the circumference of a planet he already assumed to be spherical. And probably would have even without Aristotle's proofs from 90 years earlier.

Answer 4

Scientists worked it out with theory and then direct observation.

If you go to a place that is essentially flat, you can see the horizon stretching around you.
With sensitive instruments it is possible to measure the curvature of the Earth. Couple this with the sailing vessels that circumnavigated the globe and its a pretty good argument that was in place hundreds of years before space travel.

Don't forget that Telescopes have been around for an incredibly long time so the early Astronomers could see other planets that were all round.

Its an easy leap to state that, as the other planets surrounding us, as well as the star Sol, are round or globe shaped then the Earth will follow the same Laws and also be round.

Answer 5

The ancient Greeks realized that the Earth was round by the curve of the horizon and the shadow on the moon during lunar eclipses.
Aristotle was the first to logically determine that the Earth was a sphere.

Answer 6

The Ancient Greeks, or probably even earlier civilisations worked it out. One clue is that when watching a sailing ship in the distance, the mast is the last thing to disappear. If the Earth were flat it would just keep on shrinking, or fall off if you could see that far!

Answer 7

Columbus had an inkling that the world was round but he dare not say so because the Catholic Church believed in the flat earth philosophy. He set sale West for India and when he reached those Islands near America he thought that he had reached India. Hence they called them the West Indies. The Vikings were believed to have reached America via the Arctic Circle so they to would have known that the world was not flat. After Columbus many set sail west to circumnavigate the world among them Drake and Raleigh. It soon became evident that the world was a sphere and the church had to back down. In those days the Church hated admitting they were wrong.

Answer 8

Through careful observation and measurement. Amazing what you can deduce through scientific observation. People compared a shadow at a specific time to a shadow at another geographical location at the same time - because the height of the shadow was different, the earth couldn't be flat, the sun was hitting the earth at different angles. Geometry and patience will go a long way.

Answer 9

"The Greeks discovered that the earth is round by observing lunar eclipses (i.e. when the earth blocks the sun from the moon, casting its round shadow on the moon's surface).

Another method is simultaneously measuring the length of the shadows cast by identical poles perpendicular to a flat surface that is tangential to the earth's radius at various, distant locations. If indeed the earth is round, then the shadows should all vary in length from one distant location to another, which means that the angle at which the parallel rays of sunlight struck each pole varied from one location to another. (recall the alternate-angles theorem from Geometry class) If the earth is flat, then the lengths of all the shadows should be identical when measured simultaneously, since all rays of sunlight that strike the earth are parallel. However, they are not identical, but in fact, varies in such a way that the angles indicate a spherical surface. (This was one of the earliest methods to determine the radius of the earth)"

Basically if you walk far enough, the earth naturally curves.

Answer 10

Captain Columbus (i think,was his name!) started his journey from one country, then ended up at the same country,after some years of sailing, which means he went around. during his sail, he discovered, the world was round. When he was looking through his binoculars, across the sea, he saw the top part of a sail of a ship, then finally the whole ship emerging up. Hope this is simple enough to understand.