The aurora display you can be looking at starts with huge solar eruptions, solar flares, that hurl clouds of plasma into space. These eruptions are majestic and powerful, more powerful than anything we will ever see here on earth. This solar activity is related to sunspots.
The plasma travels through space at incredible speeds. It contains electromagnetic particles, invisible to the human eye. Earth’s magnetic field diverts most of this “solar dust” away from us. But if the flare has been powerful enough, some of the dust gets through the field and is drawn towards the magnetic poles of earth. The speed increases and when the particles enter the atmosphere the are traveling at a speed of about 20.000 km/sec. To put that in perspective, it means that the particles could travel from the north pole to the south pole in two seconds.
As the particles travel through the atmosphere they collide with atoms in the top layers, the stratosphere. The collisions are very powerful, and even if the atoms and the plasma particles are too small to see, it’s the effect of these collisions that we are looking at when we stare into the colorful display of the aurora. At an altitude between 80-200 kilometers we are witnessing a display of what happens when some of the smallest parts of our world collide with the material produced in events that could easily engulf our planet.
We highly reccomend this video on youtube.com for better explanation of this process. We don’t own any rights on the video that originally comes from the University of Oslo.