An incredible cloud phenomenon appearing to stretch thousands of miles across the Earth has sent conspiracy theorists into a frenzy.
The cloud resembles a contrail emitted by an airplane but is much longer, seemingly reaching from pole to pole.
It was spotted this week by an eagle-eyed space fan watching a public live feed from the International Space Station.
The mysterious clip was later uploaded to YouTube, baffling conspiracy nuts.
One commenter wrote: “It is a portal for things to travel through unseen/stealth.”
Another quipped: “Looks MAN MADE…don’t you think we should have answers for this???????”
But it turns out the strange line has a far simpler explanation. The line is simply a rare form of cloud.
David Schultz, a Professor of Synoptic Meteorology at the University of Manchester, said he believes a low-pressure storm is responsible.
“It looks like the back edge of a cloud associated with an extratropical cyclone, i.e. a low-pressure system. It’s unusual, but it is real,” he said.
Satellite images show that a chunk of cloud did appear in the vicinity of the line on March 4, experts at the Met Office told The Sun.
It appears to stretch across a massive portion of the Earth because of a trick of the light.
“Combined with the camera’s perspective, this is making you think there is a very large shadow covering a big chunk of the earth,” a spokesman said.
The perspective trick makes the cloud appear “farther and straighter” than the image would have you believe, he added.
Looks like it’s tough luck for conspiracy fans, although perhaps it’s comforting to know a UFO wasn’t blitzing across our skies.