Christopher Columbus did prove to people before he had ship out to sea. He knew the earth was round because he himself study the Holy Bible where it proclaimed the earth was circles. Many people in the past would say it was the America legend Christopher Columbus eye who discover it shape or Aristotle the one of the ancient Greek man nor Ferdinand Magellan one of the Portuguese explorer of the ancient nor Persian or Babylonian nor Ptolemy (Claudius Ptolemaeus)? What ever or whoever claim those ancient legend people who knew the earth was always shape circle like the moon, may be right but they are wrong about how and who really first knowledge or discover it. Most likely people would had not check or miss out how the historical of the Holy Bible itself would say about the earth shape. Bible always have a way to reproof us. What ever we need to proof of what or how people proclaimed. Did you know that King Solomon or Prophet Isaiah during the Old Testament time were the first two who knew the earth were shape circles before any of those ancient legend people proclaimed? Look up in Proverbs chapter 8 verse 27; “When he (God the Father) prepared the heavens, I (Son of God)[was] there: When he (God the Father) set a COMPASS upon the face of the depth:” What it said is how Solomon wrote was told by the Son of God explaining to him how He was form before the create of circles of earth. The word for COMPASS which you may not know what it mean, it mean: 1. (verb) compass drafting instrument used for drawing circles 2. (verb) circumnavigate, compass travel around, either by plane or ship "We compassed the earth" Now for Prophet Isaiah, proof to this one is found in the book of Isaiah chapter 40 verse 22; "It is he that sitteth upon the circle of the earth, and the inhabitants thereof are as grasshoppers; that stretcheth out the heavens as a curtain, and spreadeth them out as a tent to dwell in:" Bible proclaimed the earth circles way before Christopher Columbus or any other ancient legend people. Some of those legend people happened already knew the earth were circles because they learned it right from the bible. That where many people didn't realize that it is not the legend people eye by how they discover the world earth it round but how they saw the word of God who proclaim it's knowledge first. If we carefully read their historical, we may will find that they had proclaimed by the bible alone then their self. Isn't that cool? PRIDE TO THE GOD!