How did people in olden days found out that earth was spherical in shape & not a flat plane

And how the hell did Galileo find out that earth was revolving around sun just by using a telescope??

Please answer these two questions it's killing me.... Thank you!

P.S.- Please mention all the ways that they used, in that first question.

The Ancient Greeks were aware the Earth was round based on the observations of lunar eclipses (Earth's shadow on the Moon) and ships disappearing over the horizon. Eratostenes first accurately measured the circumference of the earth around 200 B.C. People have known the earth is round for a very long time.

Galileo found the Earth (and the rest of the planets) revolve around the Sun by observing Jupiter and its moons, showing not everything orbited the Earth, and by observing Venus, which goes through phases just like the Moon does. Since Galileo could see it in both full and crescent phases when it was near the Sun, it must go around it and at those times it was either on the near side or far side of its orbit.

Well the story is long and boring but pretty much a guy named Nicolas Copernicus (also noted for his heliocentric theory) came with the idea of a round earth that was first recognized by science however the person who ACTUALLY discovered a round earth was pythagerous (however you spell it) who used light rays from the sun and proved that at the same time of day light rays at one point on earth would curve over the oceans horizon and used this to develop pythagerean theorem and he predicted the circumference of the earth as well. As for gallaleo (i can't spell names lol) he would watch Venus through his telescope and noted that Venus goes through phases just as the moon does he then theorized that this was because it went around the sun not the earth. This later lead to him concluding all the other planets, including earth, did as well. Hope that answers the question

The way of telling the earth was a sphere was that the tall sailing ships could be seen far out to sea. And first only their mast were visible as they got closer more of the mast, and finally the ship could be seen. It was how Columbus got the idea the earth was not flat. Surely the Vikings figured that out 500 years earlier.

why dont you actually do some research on your own, instead of asking unreliable sources on Y! Answers? you will most likely find the correct answer more quickly by just searching on your own.

The stars were much more visible back then. They just spent a heck of a lot of time watching the heavens