Mysterious Growing Spiral Light Spotted Over New Zealand Sky

Stargazers in New Zealand have spotted a strange spiral light in the night sky, with many flocking to social media to discuss the mysterious light show.

The spiral formed over the South Island at around 7:30 p.m. local time on Sunday, and was seen by people in Queenstown and Motueka, according to the New Zealand Herald. Eyewitnesses say that the spiral wasn't stationary, rather, it was drifting northwards.

Alasdair Burns, a stargazing guide and photographer at Twinkle Dark Sky Tours on Stewart Island, told the Guardian: "It looked like an enormous spiral galaxy, just hanging there in the sky, and slowly just drifting across."

"It looked like a planet or star," local Augustine Matthews told news site Stuff. "It was just a white dot with a tiny spiral. And within 10 minutes it had traversed half the sky and the spiral had grown three times in size. It wasn't blinking or twinkling, and it was moving fairly fast."

Many people on social media speculated that the true cause of the spiral might be extraterrestrial in nature.

One commenter joked that it was a "premonition from our orbital black hole," with another saying that it was "aliens at it again."

As ever, the truth is slightly less exciting than our imaginations.

According to Richard Easther, a University of Auckland physics professor, the spiral was caused by a rocket exhaust plume being lit up by the sun.

"When the propellant is ejected out the back, you have what's essentially water and carbon dioxide–that briefly forms a cloud in space that's illuminated by the sun," Easther told the Guardian. "The geometry of the satellite's orbit and also the way that we're sitting relative to the sun—that combination of things was just right to produce these completely wacky looking clouds that were visible from the South Island."

The rocket in question was likely one of the SpaceX Falcon 9 rockets launching a Globalstar FM15 satellite.

Once the Falcon 9 rocket's upper stage is released, it spins and vents leftover fuel as it falls back towards the atmosphere, creating the characteristic spiral that the New Zealanders saw from below. The fuel is vented as it falls to prevent it exploding closer to the ground, which might result in debris showering over populated areas.

The New Plymouth Astronomical Society posted to Facebook that "SpaceX's Globalstar 2 FM15 was likely to have passed New Zealand around that time."

Similar patterns have been seen in the sky in the past in different locations, like the one spotted earlier this year in Hawaii and Oklahoma, and in East Africa in 2018. All of these were shown to be caused by SpaceX launches too.