The human eye can see 2.9 miles on flat land and the distance around the earth roughly is 24,000 miles. You would have to be in a airplane at best to see the curvature of the earth. You definately won't see it from a mountain top on an island
Some people only think they're intelligent.
I'll try to make this easy for you. Looking out onto a clam sea one may not see an island 100 miles away. As one ascends up a mountain and periodically looks out the top of an island 100 miles away comes into view. the higher one climbs the more of the island comes into view. At 5,000 feet the whole island is in full view and the water right up to it. If the earth was flat the island would be in full view from a perch 100 feet up at the top of a tree. I don't know how to make this more easy to understand. The "island coming up over the horizon" is proof that the earth is curved.
You made it easy the first time around.
How did humans discover that the earth is round and not flat ?
well the earth is round known to the scientists but flat to some people as they can believe. humans discovered that the world is round and not flat from the astronauts and scientist as you think of the man who first went to the moon!
While it is true that men were not able to observe the complete globe until they traveled to space, a Greek astronomer calculated that the earth was actually round about 200 B.C.E. However, the fact of it's spherical shape was not generally accepted until almost a 1000 years later.
More fascinating than that though, is the knowledge that the shape of the earth was recorded in the Bible book of Isaiah about 750 B.C.E. He wrote at Isaiah 40:22 "There is One who is dwelling above the circle of the earth." The Hebrew word translated "circle" carries the meaning of a complete, or spherical circle.
Even before that, around 1500 B.C.E. Moses (who recorded the account of Job's trails) quoted Job's observation that God was "Hanging the earth upon nothing." (Job 26:7) This is clearly contrary to the common belief of the time that the earth was not only flat, but had to be supported by something, be it the god Atlas, giant elephants, or what have you.
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