At first, Ronnie Cole thought the bright light in the sky over southern Alaska was an airplane.

Mr Cole, an Alaska Photo Treks tour guide, was preparing a portrait with two of his clients in the early hours of Saturday when he noticed “there was something weird about the light”.

“It started to create a spiral pattern, it was really small at first,” he said. “Then it came out of the clouds and the spiral was still there, and it was just getting bigger in the sky. That’s when I realized it was something else.

The blue spiral streaked through the green and red hue of the Northern Lights for about three minutes before disappearing above the treeline near Trapper Creek, about 100 miles northwest of Anchorage.

“I spent about 1,000 plus hours looking at the night sky every winter,” Mr Cole said. “I see a lot of strange things in the sky, but this was definitely the most unusual.”

It wasn’t until 8 a.m., when he returned from the tour, that Mr Cole found out on social media what it was about. As alien as the whirlwind seemed, the answer was simple: SpaceX had launched a Falcon 9 rocket in California, and the reflection of the excess fuel it released into the atmosphere likely created the dizzying pattern.

Needless to say, at the time of the phenomenon, the rest of Mr. Cole’s tour customers got out of a nearby van to get a better look.

“It was truly a surreal experience to see this ever-expanding spiral crossing the sky and coming towards us,” he said. “I didn’t even bother to move my camera, I just pressed the shutter.”

Mr Cole was one of many spectators, in person and from afar, watching the spectacle of a SpaceX rocket caressing the natural display of the Northern Lights. The rocket was launched from Vandenberg Space Force Base in California on Friday evening, carrying 51 pieces of cargo, and three hours later could be seen over Alaska. A similar spiral was observed over Hawaii in January.

Don Hampton, an associate research professor at the University of Alaska Fairbanks Institute of Geophysics, called the sighting “unique,” in part because of the specific conditions that allowed it to occur: It was a clear, dark night on the ground, and the rocket fuel or exhaust was released into the direct sunlight of the aurora, spiraling in “a long sprinkler effect”.

“If it had happened in the middle of winter, you probably wouldn’t have seen it because the shadow from the sun would have been much higher,” he said.

Mr Hampton said the rocket was likely dumping fuel high enough into the atmosphere for ultraviolet light to break it down and scatter the particles around the world. He said rocket fuel pollution was not a big concern.

The Northern Lights, the natural displays of color commonly referred to as the Aurora Borealis because of their visibility at higher latitudes, occur when charged particles from the sun collide with charged particles already present in the Earth’s magnetic field, releasing light. energy in the atmosphere that interacts with the gas to create the visible glow.

The lights attract tourists like the group of Mr. Cole and Kristen Lange, who first visited Alaska last year with her husband and now own a home just north of Fairbanks. However, she doesn’t need to leave her home in Midlothian, Texas to see an aurora. In fact, at this time of year, Mrs. Lange starts her mornings in Texas looking at the previous night’s sky through sky-facing cameras that sit atop her home in Alaska.

Cameras captured a few shooting stars, meteorites and satellites, but as Ms Lange examined the tape on Saturday morning she saw a luminous ball.

“I was like, ‘What the hell is this? She said on Wednesday. She sped up the time-lapse video as a blue whirlwind streaked across a green sky and checked out a star chart. “This time we caught Falcon 9.”

She said it was “the coolest thing we could catch”.

And it probably won’t be the last time it happens, Mr Hampton said.

“It’s just a fun sight to see, and as we continue to do more launches, especially some of the bigger ones, people will probably see them again,” Mr. Hampton said. “It’s reasonably well explained. As far as I know, it’s not the aliens that land. They may be landing, but that was no indication that they were.