ANCIENT ASTRONOMY

• Earth is spherical


  One of the earliest pieces of evidence suggesting that the Earth is spherical comes from ancient Greek astronomers. They observed that during a lunar eclipse, when the Earth passes between the Sun and the Moon, the shadow cast on the Moon is curved. This observation indicated to them that the Earth's shadow is always circular, regardless of the angle at which it intersects the Moon, suggesting that the Earth itself must be spherical.
• Hull of the ship


  As ships sailed away from observers on the shore, it was noticed that the hull of the ship disappeared before the mast and sails. This phenomenon occurs because the Earth is curved, and as the ship moves away, the curvature of the Earth gradually obstructs the lower parts of the ship from view first. This observation provided evidence against the notion of a flat Earth, as it demonstrated that the Earth's surface must curve away from the observer's line of sight.
• Eratosthenes


  An ancient Greek mathematician, and astronomer hypothesized that the rays of sunlight hitting the Earth are essentially parallel. He made this assumption based on his observations of shadows cast by objects at different latitudes on Earth.
• Lunar eclipse


  During a lunar eclipse, when the Earth passes between the Sun and the Moon, the Earth's shadow is cast onto the surface of the Moon. This shadow appears curved, and its curvature matches the expected shape of a spherical object.
• Apparent position of certain stars


  Greek sailors, as they traveled farther from coastlines, noticed that the apparent position of certain stars changed. Specifically, they observed that some stars appeared higher or lower in the sky depending on their latitude and the distance from the coastline. This change in the apparent position of stars suggested to them that the surface of the Earth was curved rather than flat.