The glowing spiral was seen drifting above the UK about a day ago, and was caught on multiple cameras.
But the Met Office told curious sky-gazers there was a probable explanation.
”This is likely to be caused by the SpaceX Falcon 9 rocket, launched earlier today,” the agency posted on x.
“The rocket’s frozen exhaust plume appears to be spinning in the atmosphere and reflecting the sunlight, causing it to appear as a spiral in the sky.”
The plume faded after a few minutes.
Lander’s incredible close-up shot of the moon’s hidden side
The SpaceX Falcon 9 rocket launched from Florida just over a day ago, on a classified US government mission.
The rocket is designed to deliver a payload into space before returning to Earth.
SpaceX on X confirmed the rocket had returned to the landing zone.