On the Origin of the Aurora Borealis

It has been assumed by Birkland, Strömer, Vegard and others that the aurora is caused by charged particles from the sun which are diverted to the polar regions by the magnetic field of the earth. There are possible objections to this and it is suggested that the aurora is due to ultra-violet light of the sun which produces ions and electrons in the high atmosphere of the earth above 200 km or so. These diffuse along the magnetic lines of force, concentrate at the magnetic poles of the earth, recombine and in some way yield up their energy to form the aurora. The total aurora energy during a strong display is estimated to be ${10}^{15}$ erg ${\sec }^{-1\mathrm{}}$, which is in rough agreement with the energy of the upper spray of photoelectric ionization in the high atmosphere indicated by wireless telegraphy.