Chapter 6: Particle Interactions with Matter

One remarkable example of charged particle interaction is the aurora borealis, the beautiful display of lights seen at high northern latitudes on Earth. In the aurora borealis, charged particles from the Sun (electrons and protons) interact with the upper atmosphere of the Earth, exciting the oxygen and nitrogen molecules there. As these excited atoms relax, they give up energy by releasing photons at specific energies (colors) related to the quantum levels in those atoms. These lights are strongest at northern latitudes due to the funneling of charged particles along the magnetic field lines of the Earth. For an example of these remarkable northern lights, see the video.