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What happens to the solar wind at Earth’s bow shock?

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Diagram of Earth's atmosphere layers-troposphere, stratosphere, mesosphere, and thermosphere-showing how temperature and air pressure change with increasing altitude, with key features like the ozone layer and pressure percentages at various heights. — Ionosphere and magnetosphere The layers of Earth's atmosphere, with a yellow line showing the air temperature at various heights.

When the solar wind—a stream of charged particles—encounters Earth’s magnetic field, it meets an obstacle that prevents it from directly impacting the planet. The bow shock acts as the boundary where this high-velocity plasma flow is deflected around the magnetosphere.1

At this shock wave, the solar wind's flow of charged particles is diverted around Earth, effectively shielding the planet. Ahead of this boundary, the solar wind remains undisturbed, but upon crossing the bow shock, the particles enter the magnetosheath. This region is characterized by magnetic turbulence, where the magnitude and direction of the magnetic field vary erratically due to the production of magnetohydrodynamic shock waves caused by the high-velocity solar wind particles.12

Ultimately, this interaction creates a teardrop-shaped region of space known as the magnetosphere, which protects the Earth by forcing the solar wind to flow around it, trailing off into an elongated magnetotail on the side facing away from the Sun.12