There are many motivations for the study of the bow shock. Among these are the fast magnetosonic waves which steepen to form spatially localized shock waves, named shocklets! Creation of shocklets by the bow shock is not quite reproduction, but is close enough to stir the imagination and make one marvel at its parallelism to live organisms. The foreshock is populated by a variety of electrostatic and electromagnetic waves, making it a great natural laboratory for studies of nonlinear wave-particle interactions.
The interaction between the solar wind and the reflected particles forms the foreshock, a region extending many Earth radii upstream of the shock. As part of the dissipation process, electrons and ions are reflected off the shock. In some regimes, the transition from upstream to downstream takes place on short ( ∼100 km) length scales, while in others, the shock transition is masked with an extended region of electromagnetic waves and turbulence. Depending on the upstream Mach number (ratio of the solar wind speed to the sound speed) and location on the paraboloid surface of the shock, a different strategy for dissipation of the flow energy into heat is utilized. What we have found is a truly fascinating and complex story which is a testament to the creativeness of the bow shock. A bigger challenge, however, has been for us to use space age technology and supercomputers to find out how the bow shock does it! We have made much progress many of the pixels are in place but the picture is not complete. But unlike the usual shock waves, it has to accomplish the task without the use of collisions quite a challenge indeed.
As one would expect, its goal is to decelerate and divert the supersonic solar wind flow around the magnetosphere. The bow shock, the topic of this paper, is one of the inhabitants of this zone and it forms due to solar wind interaction with the Earth's magnetic field. They seem to have an instinctive desire to accomplish certain tasks, and devise many creative strategies to achieve their goal. These fascinating, and often nonlinear systems exhibit characteristics which in many ways mimic that of simple biological organisms. Between the world of living organisms and inanimate objects exists a zone inhabited by animate, but nonliving, physical entities.
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