The light was simply the result of excess fuel released by a SpaceX rocket launched from California about three hours before the spiral appeared, reported the Associated Press (AP) agency.

"Sometimes rockets have fuel that needs to be disposed of," explained space physicist Don Hampton, a professor and researcher at the Fairbanks Geophysical Institute at the University of Alaska.

"When they do that at high altitudes, that fuel turns into ice. And if you happen to be in sunlight, when you're in darkness on the ground, you can see it as a kind of big cloud and sometimes as a whirlpool. ", he added.

While it's not a common sight, Hampton said he's seen such occurrences about three times.

The appearance of this spiral was captured by the Geophysical Institute camera and widely shared.

"This spiral has created something of an uproar on the Internet," Hampton said.

Photographers who capture the famous northern light have also posted their photos of the light blue spiral on social media.

The rocket that lifted off from Vandenberg Space Force Base in California on Friday night was carrying about 25 satellites.

"The timing was ideal, they did some kind of fuel dump at that moment and we got that spectacular spiral", he stressed.

Although it looked like a galaxy flying over Alaska, the expert guarantees that it wasn't.

"I can tell you it's not a galaxy. It's just water vapor reflecting sunlight," he concluded.