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A bow shock is a bow-shaped (arc-shaped) shock wave caused by an object moving through a surrounding medium at higher than the medium's speed of sound. Unlike other shock waves, it is somewhat in front of the object rather than touching it. In some cases, a supersonic jet produces a bow shock in the atmosphere. A star or planet (e.g., Earth) can cause a bow shock in the medium surrounding the star's or planet's magnetosphere. The solar system was assumed to cause such a shock in the interstellar medium but recent data suggests it does not, implying that the relative speed of the solar system through the surrounding medium is subsonic.