We examine the stability of the Venus ionopause in light of the importance of gravitation and curvature. Using a one fluid approximation for the equation of motion of the plasma, and ignoring the effects of neutrals, we obtain a dispersion relation that includes the effects of magnetic field, sheared plasma flow, byouancy, centrifugal force and magnetic tension due to boundary curvature. We find that buoyancy acts to neutralize the flute instability. As expected, the Kelvin-Helmholtz mode is the dominant instability over most of the dayside ionopause. The expected growth times of this mode are short in comparison with the wave convection time over the boundary; the waves can grow and saturate quickly, producing a turbulent boundary that may affect electrodynamic coupling between the solar wind and ionospheric plasmas.