Planetary Mach cones - Theory and observation

Abstract

The asymptotic behavior of planetary bow shocks and the ability of gas dynamic theory to describe it are studied. Spacecraft observations at Venus, earth, and Mars are used to model the shapes and positions of their distant bow waves. The measured planetary Mach cone angles are compared with the mean sonic and MHD fast wave Mach numbers at 0.7, 1.0, and 1.5 AU to assess the downstream influence of the interplanetary magnetic field. Numerical gas dynamic flow solutions extending to 50 obstacle radii behind each planet are obtained and tested against the observed location of the downstream bow shock.