The region which is dominated by the planetary magnetic field is called the magnetosphere.

Its dominating pressure is exerted by the magnetic field and the trapped charged particles within the magnetosphere while in the surrounding interplanetary space the dominant pressure is created by the solar wind.

This external pressure compresses the planetary dipolar field at the dayside and forms a long magnetotail on the nightside.

The magnetosphere traps many particles near the planet and, more importantly, shields most of the planet from the solar wind flux.

Charged particles in the planetary magnetospheres can originate from different sources and are generated by a large variety of mechanisms. For instance, neutral particles can escape the atmosphere of a planet or can be knocked off its atmosphere or surface of a moon. These particles can be ionized due to UV radiation from the sun or collisions with other particles and also contribute to planetary plasmas.


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