Kiwis gazing up into the night sky on Sunday might have spotted a strange sight: a mysterious glowing swirl high above the country.
Multiple New Zealanders captured images of the event and shared them to social media.
The unusual apparition has led to much confusion over its cause, with some speculating whether it was an astronomical phenomenon - or even whether it had extraterrestrial origins.
But experts say the cause is more prosaic - a dying SpaceX rocket stage. According to spaceflightnow.com, SpaceX made three launches over Friday, Saturday and Sunday - the last one a Falcon 9 rocket carrying a Globalstar FM15 satellite.
After releasing its payload, the upper stage of the rocket spins and vents fuel - and this vapour trail then reflects the sunlight, creating the highly-visible swirl visible from the ground.
"The 'spiral' that was seen in the sky tonight around 7:30pm was most likely a fuel dump from a SpaceX rocket launch," the New Plymouth Astronomical Society posted to Facebook.
"Similar effects have been seen before, and SpaceX's Globalstar 2 FM15 was likely to have passed New Zealand around that time."
Regardless of the cause, it's an amazing sight that has Kiwis talking.