Peculiarities of solar-wind flow around the magnetosphere and the magnetopause position

MHD problems of solar wind interaction with the Earth's magnetosphere on the day-side are investigated. These ideas are used for the analysis of satellite data on the day-side magnetopause crossing. It is shown that the observed regularities may be adequately explained within the bounds of MHD-flow theory which includes the stagnation line at the nose of the magnetosphere. The ratio k of the magnetic field pressure to the plasma pressure in the vicinity of the subsolar point of the magnetosphere, which determines the magnitude of the interplanetary magnetic field penetrating into the magnetosphere, was estimated.