I can't always figure out where Geography ends. Does it include our atmosphere? I think so. Magnetosphere? Why not?
Of course, astronomy fascinates me, too.
At any rate, the auroras are clearly in the zone where astronomy and geography overlap.
Astrospace Now has a great podcast discussing folklore about the auroras.
I've only seen an aurora once, and it was an Aurora Australis. I was at only 32.7 degrees south latitude, in South Australia -- very far north to see them. They oscillated and shimmered like a bright green gossamer curtain. I hope to see the Aurora Borealis this coming spring, when I'll be in Alaska.
(Photo in the creative commons by Chantal Steyn.)