Arc measurement

Arc measurement,^[1] sometimes called degree measurement^[2] (German: Gradmessung),^[3] is the astrogeodetic technique of determining the radius of Earth and, by extension, its circumference. More specifically, it seeks to determine the local Earth radius of curvature of the figure of the Earth, by relating the latitude difference (sometimes also the longitude difference) and the geographic distance (arc length) surveyed between two locations on Earth's surface.^[4] The most common variant involves only astronomical latitudes and the meridian arc length and is called meridian arc measurement; other variants may involve only astronomical longitude (parallel arc measurement) or both geographic coordinates (oblique arc measurement).^[1] Arc measurement campaigns in Europe were the precursors to the International Association of Geodesy (IAG).^[5] Nowadays, the method is replaced by worldwide geodetic networks and by satellite geodesy.

^ ^a ^b Torge, W.; Müller, J. (2012). Geodesy. De Gruyter Textbook. De Gruyter. p. 5. ISBN 978-3-11-025000-8. Retrieved 2021-05-02.
^ Jordan, W., & Eggert, O. (1962). Jordan's Handbook of Geodesy, Vol. 1. Zenodo. http://doi.org/10.5281/zenodo.35314
^ Torge, W. (2008). Geodäsie. De Gruyter Lehrbuch (in German). De Gruyter. p. 5. ISBN 978-3-11-019817-1. Retrieved 2021-05-02.
^ Glossary of the Mapping Sciences. American Society of Civil Engineers (ASCE). 1994-01-01. ISBN 978-0-7844-7570-6.
^ Torge, Wolfgang (2015). "From a Regional Project to an International Organization: The "Baeyer-Helmert-Era" of the International Association of Geodesy 1862–1916". IAG 150 Years. International Association of Geodesy Symposia. Vol. 143. Springer, Cham. pp. 3–18. doi:10.1007/1345_2015_42. ISBN 978-3-319-24603-1.