Heliospheric current sheet

The heliospheric current sheet (HCS) is the wavy, disk-like surface in the solar wind that separates regions of opposite magnetic polarity — the magnetic equator of the heliosphere. It is created by the Sun's rotating magnetic field being carried outward into a Parker spiral, producing a thin current sheet where the magnetic field polarity reverses. The HCS is not a flat plane but a complex, warped structure whose shape is governed by the Sun's magnetic dipole moment and the tilt of the solar magnetic axis relative to the rotation axis. As Earth orbits the Sun, it crosses the HCS multiple times per year, encounters that produce characteristic sector structure in the interplanetary magnetic field and modulate the flux of galactic cosmic rays reaching the inner solar system.

The heliospheric current sheet is the Sun's magnetic seam — a stitched boundary between north and south that ripples through the solar system like a cosmic accordion.