With the help of a diagram explain why the Earth is called a geoid.
The Earth is called a geoid because its shape approximates a mathematical model of the Earth’s surface known as a geoid. A geoid is a three-dimensional representation of the Earth’s shape, which takes into account variations in the planet’s gravity field and the distribution of mass throughout its interior.
The Earth’s shape is not a perfect sphere due to the gravitational forces exerted by its rotation, which cause it to bulge at the equator and flatten at the poles. These irregularities in the Earth’s shape cause variations in the planet’s gravitational field, which in turn affect the Earth’s surface features like mountains, oceans, and continents. The geoid provides a more accurate representation of the Earth’s shape, which is important for surveying, navigation, and other scientific purposes.