Astronauts aboard the International Space Station (ISS) noticed an eerie cloud forming in Earth's upper atmosphere Thursday.

Scientists determined it wasn't a ghost, or even an alien; it was a missile plume.

"Saw something launch into space today. Not sure what it was but the cloud it left behind was pretty amazing," NASA astronaut Mike Hopkins tweeted, the Daily Mail reported. 

Soon after, "UFO" videos streamed in from Russia, they depicted a strange white object in the sky.

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"Russia just test fired a Topol icbm from the Kapustin Yar range on the lower Volga, to the Shary Shagan impact zone in Kazakhstan. In the past such launches have been seen over a wide area, as far away as Israel and Syria, and reported as UFOs," NBC News space analyst James Oberg reported in the Above Top Secret Forum, which took place before the sightings.

"This launch occurred about an hour before sunset at the launch site, so it would have been much harder to see. Regions farther east, where the sun had already set [say, around Omsk] would have darkened western skies but a back-sunlit launch contrail and then the typical brief spiral of warhead bus spinup," Oberg wrote.

The missile launch was part of the testing of a new warhead.

"The missile plume is not symmetric or evenly distributed," Oberg said in an email to NBC. "It seems to have some shape, even though it is composed of gas particles moving at perhaps 10,000 feet per second. They are visible because they are glowing hot, but also because they are in sunlight."

Bad Astronomy's Phil Plait brought up the currently-in-theaters move "Gravity," and suggested the phenomenon could be a deleted scene.

Oberg said a "Gravity"-like scenario was unlikely in this situation, NBC reported.

"This wasn't anywhere near a 'Gravity' Hollywood space debris cascade-triggering possibility," he said. "Topol's altitude, even while thrusting, was far higher than the ISS's, but in terms of accidental collision, [the phrase] 'you can't get there from here' applies. It never went fast enough to catch up."