The rise in periapsis altitude with time has allowed the Pioneer Venus spacecraft to begin probing the subsolar Venus bow shock. This has allowed the altitude of the subsolar bow shock to be determined by in situ observations for the first time. The observed altitude of 2280 km at the nose together with the previously determined terminator altitude can be used to infer the shape of the obstacle using the gas dynamic model of the solar wind interaction with Venus. When this shape is compared to the measured locations of the Venus ionopause (defined as the point where the magnetosheath magnetic field pressure and ionsopheric thermal pressures are equal), it is found that the observed ionopause position is too low to qualify as the obstacle. We infer that a layer of the mass loaded plasma in the magnetosheath forms the magnetic barrier.