From my correspondent Thomas Tallis:
The reason for the abnormally wide spread of the aurorais because it's negative polarity, or antiproton polarity.
This makes the colours that bit more spectacular as it not only collides with the atmospheric gasses, but the polarity excites our own magnetosphere, everything becomes far more intense.
Each colour has its own chemical composition as the gas molecules react with the incoming (anti)protons, the result is light energy.
Gases such as nitrogen - Crimson/pink/purple.
Oxygen glows red and lime green, usually the highest up in the ionosphere.
Hydrogen and Helium are responsible for brilliant purples and electric blue hues.
If you see a black patch, it's not a UFO!!
It's usually an area of some kind of ground based radiation, like a powerful transmitter. Found up in the highest regions of the ionosphere, these radio waves can block weaker patches of the solar radiation, the solar radiation is weaker than the interference so it's polarity can be altered, thus not interacting with surrounding gases, giving it an invisible appearance against a black sky.
Our ionosphere is a busy place, it's where radio waves go to die, forever bouncing around the earth until their amplitude gives out.
It's also where our communication transmissions take place. This is why solar activity can affect us so much, after it drowns satellites of course.
Sent from your local time machine specialist
Cramond Island in daylight