Simultaneous plasma and magnetic-field measurements of probable tangential discontinuities in the solar wind

Changes in magnetic-field and plasma data from Pioneer 6 across selected discontinuities are found to agree with those predicted for tangential discontinuities. Substantial velocity shears are found across the discontinuities, the largest observed being about 80 km/sec. From the observation of velocity shears and of the asymmetry in the orientation of tangential discontinuities, an East-West asymmetry in the solar-wind speed is inferred: Fast streams should tend to come from the West and slow streams from the East with respect to the average direction. This effect is discussed in relation to the rotation of the sun.