The word Geodesy, from the Greek geodaisia, literally means dividing the Earth and its simplest definition is that it is the study of the Earth’s shape and size. However, a generally accepted and more formal definition is:"Geodesy is the discipline that deals with the measurement and representation of the Earth, including the gravity field, in a three-dimensional time-varying space" This definition encompasses all of surveying and its techniques.
However, Geodesy is generally considered to be concerned only with measurements and representations of large portions of the Earth’s surface,
While surveying deals with smaller portions where the effect of the Earth’s curvature is minimal and can be ignored.
Geodesy also shares strong linkages with geophysics and geodynamics. The Earth’s gravity field affects geodetic measurements and defines the shape of the Earth through the Geoid. Variations in the gravity field can also tell geophysicists a great deal about the structure of the Earth’s crust and mantle. Geodetic tools (such as GPS) can be used to determine vertical and horizontal crustal motions, which are related to tectonic and seismic activity.
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