Lyman-Alpha Scattering and the Solar Wind

The interaction of the solar wind and the Earth’s magnetic field causes the field to be confined within a region shaped like a liquid drop. The solar wind flows past this region, the magnetosphere, without penetrating it. The precise shape of the magnetospheric boundary is of interest for hydromagnetic studies, but these usually begin from assumptions about the nature of the magnetic field. Any specification of the boundary which makes no reference to the field must therefore allow more flexibility in such studies.