Conspiracy theorists were sent into a frenzy last year when a gigantic line was seen on Google Earth.
And now, a satellite image taken on the ISS seems to show it has appeared once more.
The clip, which was posted by conspiracist MrMBB333, shows the massive “object” stretching across the surface of the planet.
“This is something in the sky above planet Earth,” he said.
“That’s not a continent – there’s nothing over there that is perfectly linear.
“That tells me, more than likely that whatever this is was in the sky.”
He then alters the contrast of the image to show the mystery sight in even more clarity.
“You can see there is definitely something there,” he adds.
“What are these things?”
“I’ve been an observer of Earth for years and I’ve never seen anything like this.
“This spans for several thousand miles.”
More than 83,000 people have seen the footage since it was posted yesterday.
“Mind-boggling is right,” one viewer wrote.
“What could be causing this? I’m not going to be able to stop thinking about this puzzle.”
Another added: “Maybe man-made HAARP style, maybe natural.”