What Does geoid Mean
Geoid is a term that, from the perspective of geodesy , allows to describe the theoretical appearance of the Earth . This mathematical science has the purpose of determining the magnitude and shape of the terrestrial globe to construct the appropriate maps. The concept of geodesy derives from a Greek word that can be translated into Spanish as “division of the earth” .
Specifically, we can determine which geoid has its etymological origin in Greek because that is how we discover it when we proceed to study its formation. In this way, we learn that this term is the result of the sum of two clearly differentiated parts, such as the word geo, which is synonymous with "earth" and the word eidos, which can in turn be translated as "appearance or visual appearance".
A geoid, therefore, is a body with an almost spherical format that shows a slight flattening at its ends . This polar flattening with its consequent equatorial broadening is due to the effects of gravitation and the centrifugal force generated by the rotational movement on its axis.
As we have mentioned previously, Geodesy, which is a branch of Geosciences, is responsible for studying the representation of the appearance of the Earth as well as its surface. But not only of it but also of the various natural and artificial forms that make an appearance in it both from a general point of view and from a partial perspective.
Specifically, this science can be divided into three specific branches:
Physical Geodesy. Dynamic, astronomical or classical is also how this aforementioned area is known, whose object of work is the definition of the proper figure of our planet.
Theoretical Geodesy. The force of gravity is, without a doubt, the axis around which this science revolves, where elements such as the rotational movement of the Earth or sea tides are also taken into account.
Cartographic Geodesy. The representation of our planet in cartographic or planimetric documents is the fundamental basis of the work of this branch of science that gives rise to what is known as stereographic or transversal projections.
Isaac Newton had already considered that the Earth was a geoid, a hypothesis later expanded by Jacques Cassini , Charles Marie de La Condamine , Louis Godin and Carl Friedrich Gauss , among other scientists.
Gravimetry is the technique for measuring the field of gravity. According to gravimetric tools, the geoid constitutes a physical surface that is defined by a certain gravitational potential that remains constant throughout its surface. In the case of the Earth , we work with the average surface of the ocean without taking into account the tides, the waves, the current and the Earth's rotation. For this reason, the appearance of the geoid is not identical with respect to the topography of the Earth, in which endogenous and exogenous forces come into play.
The format of the geoid, therefore, can be established by measuring the magnitude of the intensity of gravity at various points on the surface. The acceleration of gravity increases from the equator toward the poles.