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Solar activity and geomagnetic storms: The corpuscular hypothesis



An earlier article published in the December 6, 1994, issue of Eos traced the history of solar-terrestrial relations from 1852, when Sabine discovered that the 11-year sunspot and geomagnetic activity cycles waxed and waned in unison, to the early 1890s. The narrative here picks up in 1892, a year of fomentation that led to the development of the corpuscular hypothesis by Maunder, Birkeland, Chapman, Ferraro, and others.

Magnetism was “in the air” in 1892. This seminal year for solar activity saw several remarkable developments, not all of which were positive or bore immediate fruit, but each provided stimulus and a basis for subsequent progress.

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