Residents in Alaska got a surprise when a mysterious blue spiral appeared in skies already lit up by the northern lights.
The spiral, which resembled a galaxy, was visible on March 18, with photos and videos of the incident circulating on social media.
Don Hampton, a research associate professor at the University of Alaska Fairbanks Geophysical Institute, told the Associated Press that it was excess fuel released from a SpaceX rocket that caused the celestial phenomenon.
It was reportedly the rocket that launched from a California spaceport on Friday.
“When they do that [dump fuel] at high altitudes, that fuel turns into ice,” Prof Hampton 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.
“It created a bit of an internet storm with that spiral."
In January, another spiral appeared in the skies over the US state of Hawaii.
Astronomers that were using the cameras in the Mauna Kea Observatory caught the event, with photos and videos that quickly went viral on social media.
That spiral was also reportedly caused by a Falcon 9 rocket used to deliver satellites into orbit.
