The various proofs to show that the earth is spherical in shape are as follows:
1. Sunrise and Sunset
If the earth were flat, the whole world would have Sunrise and Sunset at the same time. But because the earth is not flat, the sun rises and sets at different times in different places of the world. This proves earth’s sphericity as the earth rotates from West to East.
2. Ship visibility
When a ship is coming from a distant horizon, a viewer will only see the smoke fist and then the mast, after which, the viewer will see the whole body of the ship as it closely approaches the harbour. So if the earth were flat, the whole part of the ship would have been seen at the same time.
3. Circumnavigation of the earth
The voyage round the world between 1519 and 1522 by Ferdinand Magellan and his crew proved that the earth is spherical, as their voyage never saw any sharp edge over which they would have fallen.
4. The circular Horizon
The earth’s horizon appears curved when viewed from a ship or a high cliff. This proves that the earth is spherical since the circular horizon widens with increasing altitude and, can only be seen on a spherical body.
5. Lunar Eclipse
The shadow cast by the earth on the moon during a lunar eclipse is always circular. It takes the outline of an arc of a circle and only a sphere can cast such a circular shadow.
6. Planetary Bodies
All observations from telescopes reveal that the planetary bodies (moon, sun, satellites and stars) have circular outlines from whichever angle you view it.
7. Driving Poles on Level Ground on a Curved Earth
When driving poles of equal length at regular intervals into the ground on a plain surface, they do not give a perfect horizontal level. The centre pole normally projects slightly above the poles at either end because of the curvature or the spherical nature of the earth. So, if the earth were flat, the poles would have the same horizontal level when viewed from either end.
8. Aerial Proof
High altitudes by rockets and satellites show clearly the curved edge or sphericity of the earth. This is the most convincing and up-to-date proof of earth’s spherical shape.