Shock wave trailing the Moon

A preliminary examination of the Explorer 35 data indicates that in the immediate vicinity of the moon, while it is in the solar wind, there is: (1) no obvious perturbation of the interplanetary magnetic field by the moon [Ness et al., 1967] and (2) no plasma flow (at least at typical solar wind velocities) on the dark side of the moon [Bridge, 1967]. The implication is that the moon does not perturb the magnetized plasma flow but simply sweeps out the plasma in a pattern previously described as undeviated flow [Michel, 1964], leaving behind the magnetic field. It is interesting therefore to examine what one would expect in a model of the moon that had such properties. This Letter details a particular consequence that one would expect: a standing shock wave behind the moon.