Seeing the Northern Lights is one thing - but have you ever seen a city up there?

Yes, like that scene in episode 1 of the BBC’s/HBO’s 'His Dark Materials'.

Because you can indeed see cities floating in the sky. And mountains, and container ships, and all sorts of other “hey, that shouldn’t be up there!” stuff.

And the reason isn’t magic, or “dust,” or whatever - it’s simple everyday science, although, like light pillars (see my other thread yesterday) your brain may be completely flummoxed at the time.

Okay! Let’s go see some impossible things.

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