Mapping the earth's bow shock at large geocentric distances

Distant bow shock observations by Pioneer 7 and Pioneer 8 are found consistent with a regular extension of the near-earth bow shock. The orientation of the shock normal, other observations of the distant bow shock (out to 60 to 112 earth radii in antisolar direction), and fluctuations of the geomagnetic field in the upstream region are taken into cognizance. Severe distortions of bow shock geometry at great geocentric distances are also inferred.