The Northern Lights

The charged particles of the Northern Lights, or Aurora Borealis, and cosmic rays are both affected by solar activity. Charged particles (electrons) from the solar wind are directed by the magnetic field towards the northern and southern polar regions of the ionosphere. The interaction between the charged particles and the atmospheric ions of nitrogen and oxygen produces a colorful light (Figure 10). The shifting patterns in the sky are due to changes in the magnetic and electric fields along the paths of the particles streaming toward Earth.

Figure 10. Fast incoming particles strike oxygen and nitrogen gases high in the atmosphere, producing the colourful Northern lights (photons). (Figure from Davis 1992)

The aurora occur in an oval band around both the south and north magnetic poles. This oval band spreads into lower latitudes during high solar activity, and huge flows of incoming particles. The Activity of the auroras mirror the eleven-year solar cycle. During the Maunder Minimum few auroras occurred at mid latitudes. Also, when Quebec Hydro experiences a massive blackout in March of 1989, the Aurora Borealis were reported seen over the Caribbean Sea.