Alasdair Burns, a stargazing guide on Stewart Island/Rakiura, received a text from a friend: go outside and look at the sky. “As soon as we actually went outside, it was very obvious what it was he was referring to,” Burns said. He saw a huge, blue spiral of light amid the darkness. “It looked like an enormous spiral galaxy, just hanging there in the sky, and slowly just drifting across,” Burns said. A spiral of blue lights as seen from Stewart Island/Rakiura, New Zealand, on Sunday. Theories on social media about its origins ranged from aliens to foreign rockets to...