Evidence of currents and unstable particle distributions in an extended region around the lunar plasma wake

We report observations of electrostatic ion acoustic waves and Langmuir waves during a recent lunar encounter by the Wind spacecraft. These waves are observed when Wind is magnetically connected to the nominal wake and at distances greater than 8 lunar radii from the wake. When interpreted in the context of a simple time-of-flight model, these observations imply the existence of a system of currents and disturbed particle distributions that extends far into solar wind.