Abstract
An approximate solution for the steady-state interaction between a field-free streaming plasma and a magnetic dipole parallel to the stream is obtained. The free boundary (magnetopause) between the magnetic field region (magnetosphere) and the plasma is determined by the conditions that the plasma be field-free and that its kinetic pressure on the boundary balances the pressure of the magnetic field inside the boundary. The solution was derived by a combination of analytic and numerical (relaxation) methods, with an error of approximately 1% or less in the dimensions of the magnetosphere.