bow shock
  • The front formed where the solar wind encounters the electromagnetic environment of another planet such as the Earth. The Earth’s bow shock, the barrier between the Sun’s influence and the Earth’s, is at a distance of some eight Earth diameters from the Earth, whereas at the Moon the solar wind strikes the surface directly. Mars, Venus and Mercury are intermediate cases, since they have more magnetism than the Moon but less than the Earth, so that their bow shock is less than a planetary diameter from the surface of the planet.

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