ANCHORAGE, Alaska (AP) — Northern lights enthusiasts got a surprise mixed in with the bands of green light dancing across the Alaskan sky: A pale baby blue swirl resembling a star appeared in the middle of the aurora for a few minutes.
Saturday morning’s cause is a little more mundane than an alien invasion or the appearance of a portal to the far reaches of the universe. It was excess fuel released from a SpaceX rocket that launched from California about three hours before the vortex appeared.
At some point, rockets need to be fueled, said space physicist Dan Hampton, a research associate professor at the University of Alaska Fairbanks Geophysical Institute.
“When they do it at higher altitudes, that fuel turns into ice,” he said. “And if it’s in sunlight, when you’re in the dark on the ground, you can see it as a kind of big cloud, and sometimes it’s spinning.”
Although not a common sighting, Hampton said he’s seen similar instances three times.
The vortex’s appearance was captured in time-lapse on the Geophysical Institute’s all-sky camera and widely shared. “It created an internet storm with that spin,” Hampton said.
Outside the Northern Lights event, photographers also posted their photos on social media.
The rocket lifted off Friday night from the Vandenberg Space Force Base in California with about 25 satellites.
It is a polar missile that is visible over a large area of Alaska.
Fuel dump time is correctly calculated for visibility over Alaska. “We’ve got a spiral thing that looks really nice,” he said.
Although it looks like a galaxy is passing over Alaska, he assures it is not.
“I can tell you it’s not a galaxy,” he said. “It’s water vapor that reflects sunlight.”
In January, another vortex was observed, this time on the Big Island of Hawaii. A camera atop Mauna Kea outside Japan’s Subaru Telescope National Astronomical Observatory captured the swirling night sky.
Researchers say this has happened since the launch of a military GPS satellite on a SpaceX rocket in Florida.