3/13/2023 0 Comments Geodist mapIt is an idealized equilibrium surface of sea water, the mean sea level surface in the absence of currents and air pressure variations, and continued under the continental masses. The geoid is essentially the figure of Earth abstracted from its topographical features. Main articles: Geoid and Reference ellipsoid For this reason, the study of Earth's gravitational field is called physical geodesy. This applies to the solid surface, the liquid surface ( dynamic sea surface topography) and Earth's atmosphere. To a large extent, the shape of Earth is the result of rotation, which causes its equatorial bulge, and the competition of geological processes such as the collision of plates and of volcanism, resisted by Earth's gravitational field. It is also the science of measuring and understanding Earth's geometric shape, orientation in space, and gravitational field. ![]() Such geodetic operations are also applied to other astronomical bodies in the Solar System. Geodesy in the German-speaking world is divided into "higher geodesy" ( Erdmessung or höhere Geodäsie), which is concerned with measuring Earth on the global scale, and "practical geodesy" or "engineering geodesy" ( Ingenieurgeodäsie), which is concerned with measuring specific parts or regions of Earth, and which includes surveying. It is primarily concerned with positioning within the temporally varying gravitational field. The word geodesy comes from the Ancient Greek word γεωδαισία geodaisia (literally, "division of Earth"). Two early arguments for a spherical Earth were that lunar eclipses were seen as circular shadows which could only be caused by a spherical Earth, and that Polaris is seen lower in the sky as one travels South. The corresponding scientific discipline, geodesy ( /dʒiːˈɒdɪsi/), began in pre-scientific antiquity and blossomed during the Age of Enlightenment.Įarly ideas about the figure of the Earth held the Earth to be flat (see flat Earth), and the heavens a physical dome spanning over it. The history of geodesy deals with the historical development of measurements and representations of the Earth. NASA/Goddard Space Flight Center's brief history of geodesy.
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