What does the term 'flattening' refer to in geodesy?

Flattening in geodesy specifically refers to the measure of how much an ellipsoid departs from being a perfect sphere. It is defined mathematically as the difference between the equatorial radius and the polar radius of the ellipsoid, divided by the equatorial radius. This results in a dimensionless value that indicates the "flattening" of the ellipsoid at the poles compared to its width at the equator.

Understanding flattening is crucial in geodesy because the Earth is not a perfect sphere, but an oblate spheroid; thus, this concept helps geodesists and cartographers create more accurate models and calculations for mapping and navigational purposes. Recognizing that flattening quantifies this deviation allows engineers and scientists to correct measurements and enhance the accuracy of geospatial data. Hence, the definition of flattening as a measure of the deviation of a sphere from a perfect sphere captures its essential role in understanding the Earth's shape and geodetic applications.