The effect of a uniform external pressure on the ionospheric boundary of a non-magnetic planet in a steady solar wind

The interaction of the solar wind with non-magnetic planets has been investigated theoretically taking account of the dilution of a planet's gravity field with distance and a uniform static external pressure of the incident solar wind. This results in the termination of the ionospheric boundary at a finite distance on the nightside of the planet. Numerical results are obtained for the shape of the boundary for different values of the scale height of the ionosphere, and for ratios of static to dynamic pressure of the incident solar wind.