LEILA FADEL, HOST:

Good morning. I'm Leila Fadel. Stargazers in Alaska saw a rare sight while checking out the northern lights this weekend - a ghostly light-blue swirl in the sky. Researchers at the University of Alaska Fairbanks say it was excess fuel expelled from a SpaceX rocket that took off from California Friday night. That fuel turned into ice in the atmosphere and reflected light from the sun. So it wasn't a wormhole to an alien galaxy, which is either a big disappointment or a big relief. It's MORNING EDITION. Transcript provided by NPR, Copyright NPR.