To prove to her grandmother that the Earth is spherical, Rose can present the following six evidences:
- Earth’s Curvature: Rose can explain that when ships sail towards the horizon, they gradually disappear from the bottom up. This is because the Earth’s surface is curved, and as objects move farther away, they become obscured by the curvature. This phenomenon is observed by sailors and can be explained by the Earth’s spherical shape.
- Horizon Dip: Rose can demonstrate the concept of the horizon dip. If one stands at a higher elevation, such as a mountain or a tall building, they can see farther and observe more of the Earth’s curved surface. This is because the horizon appears to be lower from a higher vantage point, indicating the Earth’s spherical shape.
- Earth’s Shadow during Lunar Eclipse: During a lunar eclipse, when the Earth comes between the Sun and the Moon, the shadow cast on the Moon is always curved. The round shadow is a direct result of the Earth’s spherical shape, as a flat object cannot cast a curved shadow.
- Circumnavigation: Rose can explain that when airplanes or ships travel around the Earth, they do not fall off the edge or encounter an abrupt end. Instead, they complete a full circle and return to their starting point. This is only possible if the Earth is a sphere, as a flat Earth would have an edge or boundary.
- Gravity and Earth’s Shape: Rose can discuss the concept of gravity and how it is related to the Earth’s shape. Gravity pulls objects towards the center of mass, and for a spherical Earth, gravity is distributed uniformly in all directions. This is why objects are pulled towards the Earth’s center, regardless of their location on the planet’s surface.
- Satellite Images: Rose can show her grandmother satellite images of the Earth taken from space. These images clearly depict the spherical shape of the Earth, with a distinct curvature and the ability to see different parts of the globe simultaneously. Satellite imagery is widely available and provides visual evidence of the Earth’s spherical shape.
By presenting these evidences, Rose can help her grandmother understand that the Earth is not flat like a table, but rather a spherical body.