# Van Allen Belts: why are they where they are?

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fog37
Hello,

I understand that the two Van Allen belts (inner and outer) are toroidal regions around planet Earth where charged particles are trapped and oscillate back and forth (magnetic mirrors) between the poles.

The Earth's magnetic field exists before, between and after the Van Allen belts. So why are the two belts located where they are located and not everywhere else, i.e. why is plasma trapped in those two specific magnetic regions of space and not somewhere or everywhere else?

Maybe, this is the explanation: the confinement of certain charged particles (cosmic rays) happens because their specific charge and energy, given the strength of the Earth magnetic field where the belts are located, is such that the confinement takes place. Is that correct?

Thanks!