Astrophotographer Todd Salat was out in the early hours of April 15, 2023, hoping to capture an aurora display over Donnelly Dome near Delta Junction, Alaska. While the stunning aurora didn’t disappoint, Salat was in for a surprise: a weird spiral appeared in the sky over the summit.
“I had no idea of what I was seeing,” Salat said on his website, “but this phenomenon appears to be caused by engine exhaust from a SpaceX Transporter-7 mission that launched southward on the Falcon 9 about three hours earlier from the Vandenberg Space Force Base in California.”
This isn’t the first time a SpaceX launch has created a mysterious swirl in the night sky. One was spotted above New Zealand last year in June following a Falcon 9 launch from Cape Canaveral in Florida. In January of this year, the Subaru Telescope captured a similar spiral sighting over Hawaii.
While SpaceX has not issued an official statement about any of the spiral sightings following their launches, it has commonly been understood the Falcon 9 second stage either performed an additional burn as it was spinning, or perhaps jettisoned excess fuel to begin deorbiting.
“It is likely either exhaust from a rocket burn to bring the second stage down over the Pacific, or perhaps dumping extra rocket fuel after that burn,” said Rod Boyce, public information officer from the University of Alaska Geophysical Institute. “The spiral pattern indicates that the second stage was spinning when it exhausted the gasses. Any water vapor would turn into ice at these altitudes, and the ice would reflect sunlight where the rocket was, and make a bright cloud visible on the ground in Alaska where the sun was well below the horizon. It looks really bright in those picture, but it is likely just a few pounds of water.”
The Institute’s all-sky camera at Poker Flat Research Range also captured the April 15 spiral on video:
These spirals, while rare, have appeared from other rockets, too. The first one I recall covering for Universe Today was the so-called “Norway Spiral” back in 2009, which came from a failed Russian rocket test flight.
“It’s kind of like noctilucent clouds, but shaped into a Van Gogh-esque Starry Night painting!” Salat explained. “This all happened as it passed over Alaska during a beautiful aurora display, stunning many night-watchers including myself. Trust me, at first, I was totally bewildered! I now know it can be explained with rocket science, but during the experience, I thoroughly enjoyed the mysterious feeling of the unknown.”
Salat added that in his photo you can make out pointer stars of the Big Dipper near the top end of the spiral, and the last two stars point to the North Star to the right. “This really is galactic!” he said.
If you’d like to order a print of this stunning view, check out Salat’s webpage for this shot with more info.