The Earth is indeed round, but the curvature of the Earth is not readily apparent when we observe our surroundings from ground level. This lack of visible curvature is not a flaw in the theory of a spherical Earth, but rather a consequence of the Earth's large size compared to our immediate surroundings.
On a small scale, such as within our everyday experience, the Earth's curvature is effectively negligible. When we look out across a flat landscape or body of water, it appears flat because the curvature over short distances is extremely subtle. The human eye has a limited field of view, and objects on the horizon are relatively far away, making the curvature difficult to perceive directly.
However, there are several observations and phenomena that demonstrate the Earth's curvature:
Ship disappearing over the horizon: As a ship sails away from shore, it gradually disappears from view bottom-first. This phenomenon occurs because the ship is moving beyond the visible horizon, which is the point where the Earth's curvature blocks our line of sight.
Aerial and space photography: From higher vantage points such as airplanes or spacecraft, it becomes increasingly evident that the Earth has a curved shape. Astronauts in space, for example, can see the curvature of the Earth with their own eyes.
Circumnavigation: The ability to travel in a straight line and return to the starting point is possible due to the Earth's spherical shape. This is exemplified by the journeys of sailors, explorers, and aircraft pilots who have circumnavigated the globe.
Earth's shadow during lunar eclipses: During a lunar eclipse, the Earth casts a rounded shadow on the Moon. This shadow is always curved, consistent with a spherical Earth.
It's important to remember that our personal observations are limited to our immediate surroundings, and the curvature of the Earth becomes more apparent when we consider larger distances or change our perspective. Scientific measurements, satellite imagery, and extensive observational evidence all confirm the Earth's spherical shape.