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A couple of seasoned aurora watchers and photographers in Alaska were left bewildered over the weekend when a massive “mysterious spiral” emerged from the usual bright green bands dancing in the sky.

Todd Salat has been photographing the northern lights for years, even taking on the name “The Aurora Hunter.” But just before 2 a.m., he experienced a “first” – “an illuminating gyre in the sky” that he said was sailing through the lights and over Donnelly Dome near Delta Junction, just southeast of Fairbanks, Alaska.

He photographed the mysterious shape, which appeared to be a giant hazy and glowing spiral galaxy hovering just above a mountain in the middle of green auroras. 

And he wasn’t the only one. 

Miles away in northwest Alaska, Elizabeth Withnall had a similar sight. 

“I was out aurora watching and saw the craziest thing in the sky,” she wrote on Facebook. “I always see strange things in the sky but this was insane.” 

She also captured images that show the same massive object heavily contrasted against the night sky. 

Withnall said she was hoping the mystery spiral would lead to the emergence of a spaceship and aliens, but according to Don Hampton of the University of Alaska Fairbanks Geophysical Institute, this event wasn’t exactly related to a UFO. 

Instead, he told the Associated Press, it was actually something that he’s witnessed himself about three times – fuel being released from a rocket. 

“When they do that at high altitudes, that fuel turns into ice. 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,” he said. “…it’s not a galaxy…It’s just water vapor reflecting sunlight.” 

This particular incident stemmed from a SpaceX rocket that launched from California’s Vandenberg Space Force Base just hours before. According to Space.com, the Falcon 9 rocket had more than 50 satellites on board and lifted off at 2:48 a.m. ET. 

The dumping of the fuel just happened to happen at the right time to be visible over Alaska, Hampton said, “and we got that really cool looking spiral thing.”