MHD theory and the solar wind - magnetosphere interaction.

In this article a theoretical basis for understanding the solar wind - magnetosphere interaction and interpreting the associated phenomena is discussed. Magnetohydrodynamic (MHD) analysis provides the main foundation of present-day knowledge. Although MHD allows only a restricted study of the plasma behaviour, it offers an entry point into many problems of space plasma physics in general, and magnetospheric physics in particular. Such problems include the flow of the solar wind around the magnetosphere, and coupling between the solar wind and the magnetosphere, which gives rise to such phenomena as the auroral lights and geomagnetic field disturbances.