Sector Structure of the Quiet Interplanetary Magnetic Field

Science  18 Jun 1965:
Vol. 148, Issue 3677, pp. 1592-1594
DOI: 10.1126/science.148.3677.1592


Observations of the interplanetary magnetic field by the Imp-1 satellite have revealed a regular longitudinal sector structure in this field. The sectors co-rotate with the sun; as an average sector sweeps past the earth the magnitude of the interplanetary field decreases from greater than 6 gammas (1 gamma = 10-5 gauss) to less than 4 gammas, and the daily sum of the geomagnetic activity index, Kp, decreases from 25 to less than 10.