Right thinking

of years, but people saw it as a normal event. They believed there was no need to question it since what was happening was natural. Isaac Newton (1643-1727) was probably the first person to wonder why an apple falls from its branch. A unique thought occurred to him: Why does the apple fall downward instead of upward? This idea led Newton to discover that the Earth has a gravitational pull. That’s why objects always fall downward and never rise upward. Similarly, for thousands of years, humans believed the Earth was flat like a plain field. This idea seemed correct based on what they could see, so it was accepted as fact. Once, a thoughtful man stood on the shore by the sea. The sea seemed to stretch to the horizon. Suddenly, he saw a mark appear on the far end of the sea. It was the mast of a ship. Slowly, the mast rose until the entire ship became visible on the surface of the water. The man started to think about why this happened. If the Earth were flat, the ship would be visible all at once from a distance and up close, with the only difference being that it would look hazy from far away and clear up close. But as it actually happened, the ship appeared partially first, and then slowly the whole ship became visible. This made the man realize that the Earth has curvature, meaning it is not flat like a board but round like a ball. As the ship rose with the curvature of the Earth, it eventually became fully visible.