Disclaimer: The following material is being kept online for archival purposes.
Although accurate at the time of publication, it is no longer being updated. The page may contain broken links or outdated information, and parts may not function in current web browsers.
A Millennium of Geomagnetism
Reviews of Geophysics, 40(3), p.1-1 to 1-30, Sept 2002
David P. Stern, Laboratory for Extraterrestrial Physics
Goddard Space Flight Center, Greenbelt, MD 20771|
Appendix: A Chronology of Geomagnetism
Best read in 12-point "Times" font
- 1000 (approx) Chinese discover that lodestone floating on
"boat" prefers south-north direction.
- 1187 Alexander Neckham describes pivoted compass.
- 1269 Letter by Petrus Peregerinus describes properties of
- 1492 Columbus sails for America, notes declination changes
in mid-ocean from easterly to westerly.
- 1581 Robert Norman publishes "The Newe Attractive,"
announcing the discovery of magnetic dip (inclination).
- 1600 William Gilbert's "De Magnete": Earth itself is
a great magnet.
- 1634 Henry Gellibrand discovers the secular variation of declination.
- 1699 Edmond Halley conducts the first magnetic survey.
- 1722 George Graham discovers diurnal variation of declination.
- 1741 Graham in London and Celsius in Sweden observe
simultaneous magnetic perturbations due to the polar aurora.
- 1777 Coulomb introduces his torsion balance, later shows magnetic
forces (electric ones, too) obey an inverse squares law.
- 1801 Alessandro Volta demonstrates his "voltaic pile," the first battery.
- 1820 Oersted discovers magnetism due to electric currents.
- 1820 Ampere explains magnetism in terms of
forces between electric currents.
- 1828 Von Humboldt urges Gauss to study magnetism. Later Gauss develops
method to measure magnetic intensity and an electrical telegraph.
- 1831 Faraday discovers electrical induction, later introduces disk dynamo.
The Rosses and Sabine reach the northern magnetic pole.
- 1832 Faraday tries to detect a dynamo current in water flowing in the Earth's field.
- 1834 Gauss founds "Göttingen Magnetic Union," later (1836-9) develops
spherical harmonic analysis of the scalar magnetic potential.
- 1843 Heinrich Schwabe publishes first evidence for the sunspot cycle.
- 1851 Von Humboldt publishes Schwabe's work; sunspot cycle widely accepted.
- 1852 Sabine finds evidence that magnetic storms follow the sunspot cycle.
- 1859 Richard Carrington observes white-light solar flare, followed by large
- 1892 George Ellery Hale introduces spectroheliograph.
- 1895 Kristian Birkeland begins experimenting with electron beams and
terrellas. Henri Poincare calculates a simple motion of trapped particles.
- 1896 Pieter Zeeman discovers splitting of spectral lines emitted in magnetic field.
- 1903 Birkeland proposes the existence of "polar magnetic storms," He also
suggests aurora is caused by electron beams emitted from the sun.
- 1906 Bernard Brunhes publishes first evidence of reversely magnetized
- 1908 Hale uses the "Zeeman effect" to show sunspots are intensely magnetic.
- 1909 Douglas Mawson reaches the southern magnetic pole, at the edge
- 1912 Arthur Schuster proposes magnetic storms are evidence for a
"ring current" in space, circling the Earth.
- 1918 Alfred Wegener publishes "The Origin of the Continents and Oceans."
- 1919 Joseph Larmor proposes that magnetic fields of sunspots
may be produced by a self-sustaining dynamo action.
- 1929 Motonori Matuyama produces evidence that reversely magnetized
rocks may have originated when the Earth's magnetic polarity had reversed.
- 1930 Chapman and Ferraro suggest magnetic storms are due to plasma clouds
from the sun (not electron beams), enveloping the Earth's magnetic field.
- 1930 Alfred Wegener dies in the snows of Greenland.
- 1933 Thomas Cowling proves self-sustained dynamos are never axisymmetric.
- 1946 Walter Elsasser tries to calculate dynamo solutions.
- 1947 Giovanelli: magnetic neutral points near sunspots are site of flare
- 1951 Jan Hospers publishes study of Icelandic lavas, concludes from their
magnetization that reversals were real.
- 1952 Runcorn promotes "polar wandering" to explain magnetic
- 1955 Franklin and Burke detect radio emissions from Jupiter.
Eugene Parker proposes way for solar toroidal fields to
strengthen the poloidal field.
- 1957 Sputnik 1 and 2 begin the era of spaceflight. Fred Singer proposes
a ring current carried by trapped low-energy particles.
- 1958 Explorers 1 and 3 discover the inner radiation belt. Eugene Parker
predicts the solar wind.
- 1959 Tom Gold coins word "Magnetosphere."
Drake proposes Jupiter has a radiation belt.
- 1961 Hess and Dietz propose Earth's crust spreads out from mid-ocean ridges.
Magnetic reconnection and plasma convection in the magnetosphere
proposed by Dungey, Axford and Hines.
Babcock proposes empirical theory of sunspot cycle.
- 1963 Morley, Vine and Matthews propose that magnetic banding of the ocean
floor is produced by seafloor spreading and polar reversals.
Magnetopause crossed by Explorer 12.
Mariner 2 maps solar wind and its streams.
- 1963 IMP 1 launched, first mapping of the Earth's magnetotail.
Vanguard 3 maps the Earth's internal field from orbit.
- 1964 Akasofu, Meng et al. analyze morphology of magnetic substorms.
Braginsky. publishes solutions to the kinematic dynamo problem.
- 1965 Heirtzler produces map of symmetric magnetic banding of the ocean floor.
- 1966 Steenbeck at al propose "alpha dynamo," generalizing an idea of Parker.
- 1969 Schields, Dessler and Freeman propose a system of "Birkeland currents"
linking Earth to space.
- 1971-72 Lunar magnetic field surveyed by lunar satellites from Apollo 15, 16.
- 1972 OGO 7 observes "coronal holes", later studied aboard "Skylab."
- 1973 Zmuda and Armstrong publish map of polar "Birkeland currents."
- 1973 Pioneer 10 crosses Jupiter magnetosphere (4 December), followed
by Pioneer 11 (1974), Voyagers 1 and 2 (1979) and Galileo (enters orbit, 1995).
- 1974 Mariner 10 flies by Mercury, observes its magnetic field.
- 1975 Lowes and Wilkinson demonstrate dynamo action in the lab.
- 1979 Voyager 1 passes near currents induced by Io's motion relative to Jupiter.
- 1979 Pioneer 11 passes magnetosphere of Saturn, followed by
Voyager 1 (1980) and Voyager 2 (1981)
- 1981 First precision mapping of the Earth's field from space, by Magsat.
- 1986 Voyager 2 passes magnetosphere of Uranus.
- 1989 Voyager 2 passes magnetosphere of Neptune.
- 1994 Ulysses observes fast solar wind above Sun's south pole.
- 1997 Mars Global Surveyor observes Mars crustal magnetization, no core field.
Mapping phase, March '99--Aug 2000.
- 1997 Glatzmaier et al. use computer to simulate the Earth's dynamo and its reversals.
- 1999 "Oersted" satellite launched to map the Earth's main field.
Back to the Master List
Author and Curator: Dr. David P. Stern
Mail to Dr.Stern: earthmag("at" symbol)phy6.org
Last updated 25 November 2001
Above is background material for archival reference only.