... Field Lines . ... Charged particles--ions and electrons--can be trapped by the Earth's magnetic field. ... A fast rotation (or "gyration") around magnetic field lines, typically thousands of times each second. ... A slow drift around the magnetic axis of the Earth, from the current field line to its neighbor, staying roughly at the same distance from the exis. ... Electrons and ions, of the energies commonly encountered in the magnetosphere, tend to circle around magnetic field lines. ...