• 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
                    magnets.
• 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
                    magnetic storm.
• 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
                    rocks.
• 1908       Hale uses the "Zeeman effect" to show sunspots are intensely magnetic.
• 1909       Douglas Mawson reaches the southern magnetic pole, at the edge
                    of Antarctica.
• 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
                    energy release.
• 1951       Jan Hospers publishes study of Icelandic lavas, concludes from their
                    magnetization that reversals were real.
• 1952       Runcorn promotes "polar wandering" to explain magnetic
                    reversals.
• 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.

Author and Curator:   Dr. David P. Stern
     Mail to Dr.Stern:   earthmag("at" symbol)phy6.org

Last updated 25 November 2001