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  2. Geopotential spherical harmonic model - Wikipedia

    en.wikipedia.org/wiki/Geopotential_spherical...

    As P 0 n (x) = −P 0 n (−x) non-zero coefficients J n for odd n correspond to a lack of symmetry "north–south" relative the equatorial plane for the mass distribution of Earth. Non-zero coefficients C n m, S n m correspond to a lack of rotational symmetry around the polar axis for the mass distribution of Earth, i.e. to a "tri-axiality" of ...

  3. Expanding Earth - Wikipedia

    en.wikipedia.org/wiki/Expanding_Earth

    Paleomagnetic data has been used to calculate that the radius of Earth 400 million years ago was 102 ± 2.8 percent of the present radius. [32] [6] Examinations of data from the Paleozoic and Earth's moment of inertia suggest that there has not been any significant change of Earth's radius during the last 620 million years. [3]

  4. Geodynamics - Wikipedia

    en.wikipedia.org/wiki/Geodynamics

    Geodynamics is a broad field which combines observations from many different types of geological study into a broad picture of the dynamics of Earth. Close to the surface of the Earth, data includes field observations, geodesy, radiometric dating, petrology, mineralogy, drilling boreholes and remote sensing techniques. However, beyond a few ...

  5. Google Earth - Wikipedia

    en.wikipedia.org/wiki/Google_Earth

    Google Earth is a web and computer program that renders a 3D representation of Earth based primarily on satellite imagery.The program maps the Earth by superimposing satellite images, aerial photography, and GIS data onto a 3D globe, allowing users to see cities and landscapes from various angles.

  6. Error analysis for the Global Positioning System - Wikipedia

    en.wikipedia.org/wiki/Error_analysis_for_the...

    That is the satellites' clocks are slower than Earth's clocks by 7214 nanoseconds a day due to their velocity. Note that this speed of 3874 m/s is measured relative to Earth's center rather than its surface where the GPS receivers (and users) are. This is because Earth's equipotential makes net time dilation equal across its geodesic surface. [18]

  7. Earth Impact Database - Wikipedia

    en.wikipedia.org/wiki/Earth_Impact_Database

    The Earth Impact Database is a database of confirmed impact structures or craters on Earth. It was initiated in 1955 by the Dominion Observatory , Ottawa, under the direction of Carlyle S. Beals . Since 2001, it has been maintained as a not-for-profit source of information at the Planetary and Space Science Centre at the University of New ...

  8. Dynamic height - Wikipedia

    en.wikipedia.org/wiki/Dynamic_height

    Dynamic height is a way of specifying the vertical position of a point above a vertical datum; it is an alternative for orthometric height or normal height. It can be computed by dividing the location's geopotential number by the normal gravity at 45 degree latitude and zero height, a constant value (9.806199203 m/s 2 ). [ 1 ]

  9. Rankine theory - Wikipedia

    en.wikipedia.org/wiki/Rankine_theory

    Rankine's theory (maximum-normal stress theory), developed in 1857 by William John Macquorn Rankine, [1] is a stress field solution that predicts active and passive earth pressure. It assumes that the soil is cohesionless, the wall is frictionless, the soil-wall interface is vertical, the failure surface on which the soil moves is planar , and ...