A striking video of the contrail was taken from another plane while the Boeing 787 was flying at 33,000 feet above the east coast of Russia.
The Chemtrails conspiracy theory is one of the most supported on Earth and counted the late pop legend Prince among its high-profile advocates.
At its most bizarre extreme, it is believed the contrails which form behind jet aircraft are actually streams of toxic “mind-control” chemicals, which dilute before they reach the ground, leaving a gas we breathe in that keeps the general population in check.
But there are a growing number of chemtrail believers, who claim the conspiracy is actually a secret global plot to change Earth’s climate in the hope it will reverse the effects of climate change.
People who have viewed the video online have posted their reactions.
One poster using the name Celsius Rising said: “Condensation trails do not extend for miles across the sky, and are seldom longer than a few hundred feet in length.
“The trails that persist for many miles are something else, and I for one, would like to know what the hell is being sprayed over our heads, and why.”
Another wit the user name JR added: “Anyone with brains knows they are chemtrails that spread out across the sky and never dissipate.
“It’s all part of the global warming program.
“Sadly these chemicals are dangerous. Go to geoengineering.com if you want to be enlightened.”
However, others rubbished the conspiracy theorist’s claims.
One calling themselves Old Ollie said: “Seriously, chemtrails? Do you buy your tinfoil hats ready-to-wear, or do you make them yourselves?”
While another called McLowe said: “Chemtrail… you’re Funny! It’s called water vapour.”
The person who filmed contrail was also level headed about what they saw, writing: “This contrail looks dark against the rising sun.
He said the trails were the result of hot exhaust mixing with cold moist air.