Anomalous cosmic rays have energies of ~10⁷ to 10⁸ eV and are thought to originate from neutral interstellar atoms that have been ionised by solar UV radiation after entering the heliosphere. Once ionised, these charged particles are carried on the solar wind (and associated magnetic field) back out to the shock created where the solar wind meets interstellar space. This shock accelerates the nuclei to cosmic ray energies, some of which then return to the inner Solar System.

See also: cosmic rays.