Termination Shock Distance Expected from the Local Cloud Ram Pressure, Compared with the Voyager Crossings

The solar wind expands until its ram pressure falls to the total pressure of the surrounding interstellar medium, and that balance point is where the termination shock is expected. Computing the balance from a typical solar wind at Earth and the published density and inflow speed of the Local Interstellar Cloud places the shock near 81 astronomical units, against the 94 and 84 astronomical units at which Voyager 1 and Voyager 2 actually crossed it. The simple spherical estimate lands within about ten percent of the mean crossing distance, and the residual is in the direction expected from the known asymmetry of the heliosphere and from solar-cycle variation of the wind. The estimate uses only pressure balance and published inputs; it is a computed expectation, not a measurement, and the deposited script makes the arithmetic auditable.