The trajectory of a high-energy cosmic ray

The trajectories of cosmic rays are bent by intergalactic magnetic fields. Two variables influence a cosmic ray’s trajectory: charge and energy. Ultra-high-energy protons (low charge) have nearly straight trajectories; ultra-high-energy heavy atomic nuclei (high charge) have bent trajectories. Scientists are hoping that new observation facilities will help them understand whether the majority of cosmic rays are protons or heavy atomic nuclei.