Solar wind interactions with planets that possess neither an intrinsic magnetic field nor a significant ionosphere have not been well studied. We have constructed a model to simulate the interaction between a hot magnetized plasma and a planet containing only a neutral atmosphere. Examination of the boundary conditions that yield a physically valid solution shows that the interaction is similar to the solar wind interaction with Venus. We show that most (97%) of the incident flow is deflected around the atmosphere, and the small fraction that enters interacts in such a way as to transfer the flowing momentum through the neutral atmosphere to the planetary body. This demonstrates that the true barrier to a flowing plasma, such as the solar wind, is neither its ionosphere nor its intrinsic magnetic field, but rather the planetary body itself.