The Spiral Interplanetary Magnetic Field: A Polarity and Sunspot Cycle Variation

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Science  04 Oct 1974:
Vol. 186, Issue 4158, pp. 51-53
DOI: 10.1126/science.186.4158.51


Spacecraft observations near the earth of the average direction of the interplanetary magnetic field during the sunspot maximum year 1968 showed a deviation from the spiral field of Parker's classical description. The included angle between the average field direction when the field polarity was away from the sun and the average direction when the field polarity was toward the sun was 168°, rather than 180° as predicted by Parker. This effect appears to have a sunspot cycle variation.