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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| History of geomagnetism | 4/4 | https://en.wikipedia.org/wiki/History_of_geomagnetism | reference | science, encyclopedia | 2026-05-05T16:17:55.648373+00:00 | kb-cron |
=== Expeditions to the magnetic poles === The magnetic North Pole differs from the geographic North Pole (Earth's rotation axis), magnetic north which is the direction of north given by a compass, and the theoretical Geomagnetic pole. The search for the magnetic north pole began in 1818 with a British expedition exploring the Northwest Passage. In 1831 James Clark Ross from the ship Victory first located the Earth's magnetic North Pole on the west coast of the Boothia Peninsula (Arctic Archipelago). In 1842 the Antarctic Ross expedition inferred the position of the South Magnetic Pole, which was not formally located until the twentieth century. Since then, the North magnetic pole has migrated on a north-northwest direction, towards Siberia, and since 2017 has been located a few hundred kilometres into the Arctic Ocean. Owing to liquid motion of the Earth's core, the actual magnetic poles are constantly moving (secular variation). The poles also daily swing in an oval of around 80 km (50 miles) in diameter due to solar wind deflecting the magnetic field. The position of the North Magnetic Pole is reassessed every five years by the British Geological Survey (BGS) and the US National Oceanic and Atmospheric Administration (NOAA), which are responsible for the World Magnetic Model (WMM).
=== Magnetic observation campaigns ===
A magnetic survey (1698-1700) by the British yielded the 1702 magnetic chart of the world by Edmond Halley. Early magnetic observatories were established in Munich(1819) and Berlin (1827). Observed variations in magnetic direction, strength and dip led to determinations by Alexander von Humboldt, Carl Friedrich Gauss and Edward Sabine that the Earth's magnetic field should be systematically surveyed and monitored globally to perhaps reveal important geophysical aspects of the planet. This led to the establishment of more magnetic observatories and campaigns in Germany (Humboldtian Magnetic Association/Humboldtsche Magnetische Verein (1829–1834), Göttingen Magnetic Union/Göttingen Magnetischer Verein (1836-41)), Britain (Magnetic Survey of the British Islands (1833), British Empire, East India Company), and Russia (1841-1862). With a total of 53 stations across the globe, terrestrial magnetism became one of the most data producing geosciences of the era. This was followed by global geomagnetism campaigns during the First International Polar Year (1882–1883), Second International Polar Year (1932–1933), International Geophysical Year (1957–1958), International Year of the Quiet Sun (1964–1965), International Year of the Active Sun (1969–1971), International Magnetospheric Study (1976–1979), and Fourth International Polar Year (2007–2008).
== See also == History of geophysics Timeline of electromagnetic theory Rhumbline network
== Notes and references ==
== Further reading ==