The solar wind geomagnetic field boundary

The theory of the boundary of the cavity surrounding a magnetic dipole immersed in a steadily flowing stream of plasma is reviewed, and the various results are compared with satellite observations of the termination of the geomagnetic field. The shape on the solar side as roughly hemispherical with an indentation near the poles; the shape on the antisolar side is probably that of a raindrop, but it depends critically on the direction and relative magnitude of the interplanetary magnetic field and possible nonadiabatic processes in the boundary transition layer.