Again, it is a planet, though TES religions don't know as much. Also, there's plenty of land north of mainland Norway (Svalbard), but they still have northern lights.
Atmora was a continent. There's no continent north of Norway. And whether Nirn is a planet or not is really up for debate. Personally I don't think it is. It's a plane, yes, but not a planet, But let's not go into a discussion about what would actually work on Nirn like it does on earth and what won't, because it's a tiring discussion without a desirable outcome for anyone.
My main point is this: I'd love them to make something inspired by Aurora Borealis, but I'd hate it if they downright copy it. Make it something unique to TES with a unique flavor and I'd really like to see it in the game.