Is the world really round?

If the world’s surface could be smoothed out and the tides ceased, our planet would be a shape called an ‘oblate spheroid’, or a squashed sphere bulging around the equator. In reality, Earth doesn’t have a uniform shape, as there are higher parts (mountains) and lower parts (oceans).

The term for this type of generalised shape is a ‘geoid’, although the variation of Earth’s surface to the averaged out geoid surface is very small – less than the relative thickness of an apple skin to an apple.