He didn't. It was well-known at the time of Columbus that the earth is round.
He thought the earth was flat and it is round
The earth is flat
Columbus never believed the earth was square, in fact, the myth was that he believed the earth was flat. However, in truth, Columbus did not believe the earth was flat. Ancient Greek mathematicians, Pythagoras and Aristotle, proved the earth was spherical in shape based on the shadow of the earth on the moon and the curvature of the earth when approaching land. Columbus falsely believed he could reach Asia by going west because he underestimated the circumference of the earth, and also believed Europe was wider than it was.
Round. Most people by the time of Columbus did not believe the Earth was flat, despite what some history books will tell you.
The earth is flat
He didn't. It was well-known at the time of Columbus that the earth is round.
Yes.
No, most educated people in Columbus's time did not believe the Earth was flat. By the 15th century, ancient Greek scholars had already proven that the Earth was a sphere. Columbus's challenge was not convincing people the Earth was round, but rather estimating its size and the distance to Asia.
false
He was trying to prove that the earth was flat
Because the curvature of the earth is so gentle, do to it's size, people couldn't understand how it could be curved as it looks flat.
The majority of the members of the Flat Earth Society do not believe the Earth is flat. They are members because it's a counter-culture group which some people find interesting.Those who think the Earth is flat are usually motivated by religious literalism.