Here are four pieces of evidence that demonstrate the Earth is spherical:
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Horizon and Ships: One of the earliest observations comes from the way ships appear and disappear on the horizon. As a ship approaches, the top of the mast becomes visible first, and the hull appears last. Conversely, when a ship leaves port and sails away, the hull disappears before the mast. This phenomenon occurs because the surface of the Earth is curved. If the Earth were flat, we would see the entire ship at the same time until it was far enough away that it became too small to see.
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Lunar Eclipse: During a lunar eclipse, the Earth casts a shadow on the Moon that is always round. Regardless of the Earth’s position relative to the Moon and Sun, the shadow is curved. This consistent round shadow is only possible if the Earth is spherical. The ancient Greeks, including Aristotle, recognized this and noted that the shadow’s roundness was evidence of the Earth’s spherical shape.
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Different Star Constellations: When traveling south from the Northern Hemisphere to the Southern Hemisphere, travelers notice that different constellations become visible, and some familiar stars gradually disappear from view. This change occurs because of the curvature of the Earth, which blocks certain stars from being seen as one moves further away. If the Earth were flat, we would see the same night sky regardless of our location.
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Satellite Images and Gravity: Modern technology has provided direct visual evidence of the Earth's shape through photographs taken from space. Satellites in orbit around the Earth capture images that clearly show the planet as a sphere. Furthermore, the force of gravity pulls objects toward the center of mass, leading to the spherical shape of celestial bodies, including planets. This phenomenon is consistent with the laws of physics and supports the conclusion that the Earth is a spheroid.
Together, these proofs provide robust evidence of the Earth's spherical shape from various observations and scientific principles.