The termination shock near 35° latitude

Abstract

The termination shock moves outwards and inwards over timescales of a solar cycle in response to the variations in the average solar wind speed. The amplitude is greater than 50 AU near 35° latitude; the maximum (minimum) distance occurs during the rising (declining) phase of the solar cycle. Shock parameters are distinctly different when the shock moves outwards or inwards. During the period of high-speed (low-speed) solar wind, the shock moves outward (inward) and the shock is weaker (stronger). This study assumes that the first crossing of Voyager 1 with the termination shock occurred at 85.5 AU on 2002.6. If Voyager 1 did cross the shock in 2002.6, the spacecraft would likely cross the shock at least two more times before 2010, but no second crossing would occur close to 2003.1. If Voyager 1 did not cross the shock in mid-2002, it might still do so before 2005.