The video – captured from a plane window – shows a mysterious light beneath the clouds.
It is reported to have been spotted while travelling over a huge empty part of Russia.
As the jet speeds over the top, the light it remains completely still – suggesting it is coming from a fixed area on the ground.
It was uploaded by YouTube account Stan on April 22 and has since gained popularity from other conspiracy channels.
One user – named thirdphaseofmoon – shared the clip on his profile with the title “Russia probably doesn’t want you to see this”.
He said: “It seems like it is out in the middle of nowhere.
“What kind of light would be emitting this bright orange mysterious glow?
“Maybe a UFO crashed? Or UFO experiments are taking place.”
Many American’s believed this photo to prove the existence of UFO
Since he uploaded the video today – it has gained a mass of popularity – racking up more than 6,000 hits.
And viewers were quick to speculate what it could be.
One comment read: “That light is too concentrated and uniformed to be a fire – very unusual indeed.”
And another added: “That could be a UFO below the clouds.”
Before a third claimed: “Russia has a big UFO base.”
But some were not so convinced, writing it off as lens flare or some kind of natural weather event.