  We show that that an interstellar magnetic field can produce a north/south
asymmetry in solar wind termination shock. Using Voyager 1 and 2 measurements,
we suggest that the angle $\alpha$ between the interstellar wind velocity and
magnetic field is $30^{\circ} < \alpha < 60^{\circ}$. The distortion of the
shock is such that termination shock particles could stream outward along the
spiral interplanetary magnetic field connecting Voyager 1 to the shock when the
spacecraft was within $\sim 2~AU$ of the shock. The shock distortion is larger
in the southern hemisphere, and Voyager 2 could be connected to the shock when
it is within $\sim 5~AU$ of the shock, but with particles from the shock
streaming inward along the field. Tighter constraints on the interstellar
magnetic field should be possible when Voyager 2 crosses the shock in the next
several years.
