Paul's Ride Guide: Northern Lights Southern Lights

I've seen the northern lights, or "Aurora Borealis", quite a few times this year at our camp which is north and west of Calgary, including an awesome display on the last weekend of May that went on for several hours and lit up the entire sky. Always awe inspiring to see and it gives me a sense of good fortune whenever we're blessed with a sighting, particularly when they're of such duration.

In the telling of our sightings it was quite surprising to know that many people have never seen the northern lights at all. It just seemed a 'Canadian thing", since witnessing them all my life. Then there was also the surprise of a conversation about the southern lights, when someone called bullshit on me for saying it was an actual phenomena, to the point where they got out their phone and did an internet search. And yes, the "Aurora Australis" is real and basically the same as it's northern counterpart, just occurring over the southern night sky and less observed, since the re are just not too many people in the Antarctic or Southern India Ocean regions.

Less surprising is that many people do not know what causes the northern (or southern ) lights, even those who have seen them. Here's what I know, supplemented by some photos I borrowed from the internet. In the most simplest terms, it is caused by the collision of charged particles released from the sun's atmosphere colliding with gaseous particles in the Earth's atmosphere. The sun's temperature is in the millions of degrees Celsius and gas molecules collisions are frequent and violent. Free electrons and protons are thrown by the rotation of the sun and escape through holes in it's magnetic field. Solar winds blow these charged particles toward the Earth, with most deflected by our own magnetic field. However, the magnetic field around the polar caps is weaker and the charged particles enter the Earth's atmosphere, collide with the gas particles and create the dancing colours we see in the sky. This can occur between 80 and 640 kilometres above the surface of the Earth, which explains the various colours, as different gases exist at different altitudes. We tend to see a lot of greenish yellow aurora around here, caused by higher concentrations of low altitude oxygen, whereas high altitude oxygen causes rarer red lighting effects. Greater concentrations of nitrogen cause blueish and purple red lights .