REFERENCE ELLIPSOID Meaning and
Definition
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A reference ellipsoid is a geometric shape used in geodesy, cartography, and geophysics as a mathematical model to approximate the shape of the Earth. It is essentially an ellipsoid of revolution, where the equatorial radius is greater than the polar radius due to the Earth's rotation.
The reference ellipsoid is designed to capture the Earth's dimensions and is used as a standard reference for measuring and representing the planet's shape, size, and variations in its terrain. It provides a consistent framework for mapping and surveying processes, allowing for accurate measurements and calculations of distances, areas, and angles on the Earth's surface.
The reference ellipsoid is generally defined by two parameters: the semimajor axis, which represents the equatorial radius, and the semiminor axis, which represents the polar radius. These axes determine the elliptical shape of the model, while the center of the ellipsoid coincides with the Earth's center of mass. Different reference ellipsoids exist, each tailored to fit different regions of the Earth, depending on the characteristics of the local geoid (a representation of the Earth's gravitational field).
Overall, the reference ellipsoid serves as a simplified yet accurate representation of the Earth's shape, enabling precise measurements and suitable frameworks for various scientific and engineering applications.
Etymology of REFERENCE ELLIPSOID
The word "reference" comes from the Latin word "referre", which means "to bring back" or "to relate". It is derived from the combination of the prefix "re-" meaning "back" and the verb "ferre" meaning "to carry" or "to bear". "Ellipsoid" is derived from the Greek word "elleipsis", meaning "omission" or "deficiency", combined with the suffix "-oid", which means "resembling" or "having the appearance of". When combined, "reference ellipsoid" refers to a mathematical model of the Earth's shape that is used as a reference in geodesy and cartography.
