[brityank]

The shock wave, or heliospheric termination shock, occurs when the supersonic wind thins to the point that it can no longer rebuff the denser haze of charged particles flowing through interstellar space. Instead, the solar wind suddenly collapses in on itself.

Uhmmm...no?

Well, I think it is a wind, but I believe that it is more shaped by the gravi-magnetic forces than by the particle stream itself. What direction, with respect to the solar system's travel direction in the cosmos, were the Voyager craft sent; the boundary distance will change and be further away the further from the dead-ahead position they travel.

[NucSubs]

No.

There is no wind in a vacuum.

There is no sound in a vacuum.

Therefore the term “supersonic” is dead wrong.