People were left baffled after a giant spiral appeared in the sky last year.
The enormous spiral appeared while people were trying to catch a glimpse of the Northern Lights, but got a bit more than they expected.
The strange phenomenon appeared on April 14 last year in the early hours of the morning, and took social media by storm.
Many people took pictures of the strange occurrence, leaving people seriously scratching their heads over what was causing it.
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The extraordinary pattern was spotted in Alaska in the US.
Among those in awe at the pattern was avid aurora-watcher Elizabeth Withnall, who shared pictures of the strange pattern to Facebook.
Withnall captioned the series of photos writing: "Ok I was out aurora watching and saw the craziest thing in the sky. I always see strange things in the sky here but this was insane."
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Photos from that fateful evening subsequently made their way across other social media platforms including X where many theorized about the origins of the strange spiral.
Of course, some people claimed it was evidence for 'extra-terrestrial life'.
Others maintained it was a bizarre sighting of the 'northern lights'.
It seems though, however, that both schools of thought were wrong.
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In reality the spiral, as many on social media pointed out, was nothing more than a rocket exhaust.
Talk about an anti-climax.
Space physicist, Don Hampton, a research associate professor at the University of Alaska Fairbanks Geophysical Institute, offered his expertise on the matter.
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He told KTUU: "After doing some online research, this phenomenon appears to be rocket engine exhaust from a SpaceX Transporter-7 mission that launched on the Falcon 9 about three hours earlier in California."
The expert continued: "Water vapor in the exhaust from the second stage engine freezes and catches high-altitude sunlight, effectively glowing and creating this spiral galaxy of a display. The payload is 51 satellites and it’s on its way to orbit."
In short, the rocket launched from California's Vandenberg Space Force and its engine exhaust released water vapor that eventually turned into ice during its fly-by over Alaska.
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Hampton added that the SpaceX rocket was able to gain altitude when it went over Alaska which is what led to it 'stunning many night-watchers'.
One of which included the likes of Alaska-based photographer and 'professional aurora hunter', Todd Salat.
Like Withnall, the photographer was also quick to whip out the camera to record the magnificent moment.
He caught the spiral expanding and moving over Donnelly Dome near Delta Junction on a 30-second time-lapse video.
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Salat told NBC: "At first I had no idea of what I was seeing, but this phenomenon appears to be caused by engine exhaust from a SpaceX Transporter-7 mission."
Mystery solved.
Kit Roberts