Mysterious glowing blue spiral appears amid Northern Lights in the skies over Alaska

A mysterious moving blue spiral resembling a galaxy left Northern Lights enthusiasts stunned as it appeared amid an Aurora Borealis display over Alaska.

The swirl emerged among the more recognisable green bands of light for a few minutes on Saturday morning and left those watching baffled as it began moving towards them.

“It got bigger and bigger,” photographer Todd Salat told the Anchorage Daily News, adding that the “beautiful piece of art in the sky” was almost directly overhead within minutes.

“I had absolutely no idea what it was… I would say this was maybe the most bizarre thing I’ve ever seen in my life.”

Pictures of the unusual phenomenon set the internet alight with talk of an approaching galaxy, but rather than announcing the arrivial of alien life, the spiral is believed to be all too human.

Experts believe the moving swirl was the result of a SpaceX rocket dumping excess fuel.

The rocket had been launched from California about three hours earlier and had jettisoned some of its fuel over Alaska, which at the high altitude had turned into ice.

Space physicist Don Hampton, a research associate professor at the University of Alaska Fairbanks Geophysical Institute said: “And if it happens to be in the sunlight, when you’re in the darkness on the ground, you can see it as a sort of big cloud, and sometimes it’s swirly.”

The appearance of the swirl was caught in time-lapse on the Geophysical Institute’s all-sky camera.

“It created a bit of an internet storm with that spiral,” Prof Hampton said.

The rocket took off from Vandenberg Space Force Base in California on Friday night with about 25 satellites onboard. As it was polar launch, it was visible over a large swath of Alaska, and the fuel dumped at just the right time for the "really cool looking spiral thing,” Prof Hampton said.

“I can tell you it’s not a galaxy,” he said. “It’s just water vapour reflecting sunlight.”

Another spiral was seen over Hawaii’s Big Island in January, a spectacular captured by a camera at the summit of Mauna Kea, outside the National Astronomical Observatory of Japan’s Subaru telescope.

Researchers have said it was from the launch of a military GPS satellite that lifted off earlier on a SpaceX rocket in Florida.

Want a quick and expert briefing on the biggest news stories? Listen to our latest podcasts to find out What You Need To Know