On the Earth's bow shock motion and speed

Abstract

The Earth’s bow shock has been shown to have often a speed rather high (50–150 km s−1) on the basis of different methods of investigation (Formisano et al.,1971; Greenstadt et al., 1972; Formisano et al., 1973; Guha et al.,1972). The causes of the shock motion and speed are not well understood, the resonant oscillator proposed by Smit (1968) being not suitable for the Earth’s magnetosphere. Shen and Dryer (1972) studied the interactions of the Earth’s bow shock with interplanetary shocks as these are causes of bow shock motions; the frequency of interplanetary shocks is rather low (1 per month) so this kind of interaction cannot be invoked to explain the bow shock motion and speed.