A Brief History of Magnetospheric Physics Before the Spaceflight Era
A BRIEF HISTORY OF MAGNETOSPHERIC PHYSICS BEFORE THE SPACEFLIGHT ERA David P. Stern Laboratoryfor ExtraterrestrialPhysics NASAGoddard Space Flight Center Greenbelt,Maryland Abstract.This review traces early resea/ch on the Earth's aurora, plasma cloud particles required some way of magneticenvironment, covering the period when only penetratingthe "Chapman-Ferrarocavity": Alfv•n (1939) ground:based0bservationswerepossible. Observations of invoked an eleCtric field, but his ideas met resistance. The magneticstorms (1724) and of perturbationsassociated picture grew more complicated with observationsof with the aurora (1741) suggestedthat those phenomena comets(1943, 1951) which suggesteda fast "solarwind" originatedoutside the Earth; correlationof the solarcycle emanatingfrom the Sun's coronaat all times. This flow (1851)with magnetic activity (1852) pointed to theSun's was explainedby Parker's theory (1958), and the perma- involvement.The discovei-yof •solarflares (1859) and nent cavity which it producedaround the Earth was later growingevidence for their associationwith large storms named the "magnetosphere"(1959). As early as 1905, led Birkeland (1900) to proposesolar electronstreams as Birkeland had proposedthat the large magneticperturba- thecause. Though laboratory experiments provided some tions of the polar aurora refleCteda "polar" type of support;the idea ran into theoreticaldifficulties and was magneticstorm whose electric currents descended into the replacedby Chapmanand Ferraro's notion of solarplasma upper atmosphere;that idea, however, was resisted for clouds (1930). Magnetic storms were first attributed more than 50 years. By the time of the International (1911)to a "ringcurrent" of high-energyparticles circling GeophysicalYear (1957-1958), when the first artificial the Earth, but later work (1957) reCOgnizedthat low- satelliteswere launched, most of the importantfeatures of energy particlesundergoing guiding center drifts could the magnetospherehad been glimpsed, but detailed have the same effect.
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