Anticipated Voyager crossing of the termination shock

Abstract

This paper studies the varying location and conditions of the termination shock over 34‐year period (1966 – 2000). The shock location is anti‐correlated with the sunspot number, moving inward or outward during the rising or declining phase of the solar cycle. For the shock in the upwind direction, plasma and magnetic field conditions in its immediately upstream are extrapolated from 1 AU data using MHD equations including pickup protons, and the shock location estimated by the ACR spectrum is used as a guide. Voyager 1 will cross the termination shock in the region of high‐speed solar wind at latitude of ∼34°. Taking into consideration the high‐latitude effects, the calculation indicates that the shock is now moving inward to within 85 AU. Voyager 1 could cross the shock before Year 2002, and the crossing may occur 3 or more times over a period of about 4 years.