Q&A for How to Prove the Earth Is Round

When a ship on the ocean is going further away it does not just get smaller and smaller, but instead the level of the ship (relative compared to you) drops, thus proving the Earth round. If the Earth was flat, then the ship would just decrease in size, not drop.

Many meteoroids and comets aren't round. For example, take a look at comet 67P: it consists of two smaller lobes. Small objects like this often have an irregular shape because they don't have enough gravity to contract into a sphere.

It's not a perfect sphere, but rather an oblate spheroid or ellipsoid, which means that the poles are slightly "squished" together and on the equator, there is a slight bulge. This happens because of the Earth's rotation. The centrifugal force pulls the parts with more mass further away from the rotational axis.

Rotation refers to an object's spinning about an internal axis. Orbiting refers to an object's movement around an external axis.

Nowadays we can watch it spin from an outpost such as the Moon. Before we were able to do that, we relied on devices such as the Foucault pendulum. See Wikipedia's article on that.

That refers to the Earth's spin around its own axis.

The Earth can be described as a "squashed" sphere, with an equatorial diameter slightly greater than its polar diameter.