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How does Earth’s magnetosphere protect the planet from the solar wind?

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Space weather Earth's full North Polar auroral oval, in an image taken in ultraviolet light by the U.S. Polar spacecraft over northern Canada, April 6, 1996. In the colour-coded image, which simultaneously shows dayside and nightside auroral activity, the most intense levels of activity are red, and the lowest levels are blue. Polar, launched in February 1996, was designed to further scientists' understanding of how plasma energy contained in the solar wind interacts with Earth's magnetosphere.

Earth’s magnetosphere acts as a protective shield by interacting with the solar wind—a stream of charged particles, or plasma, flowing from the Sun.12

Generated by an electromagnetic dynamo effect within Earth’s liquid outer core, the planet’s geomagnetic field creates an obstacle that balances the pressure of the incoming solar wind at a distance of approximately 65,000 km toward the Sun. This interaction produces a bow shock, which deflects the majority of solar wind particles around the planet.12

While the magnetosphere effectively diverts most of this high-velocity plasma, some particles can leak through the magnetopause or become trapped in the Van Allen radiation belts. By creating this teardrop-shaped region of space, the magnetosphere prevents the direct impact of solar wind on the atmosphere and surface, which is critical for protecting life from potentially harmful particle radiation.2