A Thread of History
1000 China invents the compass
1600 W.Gilbert writes De Magnete
1724 G.Graham detects “magnetic storms”
1839 C.F.Gauss needs more data on B-field
1896 K.Birkeland makes terrella exp.
1910 C.Stoermer starts dipole problem
1924 A.Schmidt says m.storm=ring current
1930 S.Chapman says “its neutral plasma”
1939 H.Alfven says “no, its charged plasma”