This strange blue spiral of light, witnessed by thousands across the northern part of Norway, has been dubbed 'Stargate' by amazed Norwegians.
Scientists were left baffled by what could have caused the eerie light show, which was like nothing they had ever encountered before.
Various suggestions were put forward, such as a meteor explosion, an unusual display of Northern Lights, an out-of-control Russian missile, or a UFO - even a space portal.
The strange display occurred at 8.45am, and lasted for two minutes, with eyewitnesses describing a bright blue tail tapering towards the ground and exploding into incandescent white Catherine wheel behind a glowing centre.
The sky continued to glow a vivid blue afterwards.
"This light spun diagonally across the heavens," said Totto Eriksen Tromso. "People just stopped and stared. It was like a Hollywood movie."
Norway's most renowned astronomer, Knut Odegaard, said that it lasted too long to be an astronomical event and was 'definitely not' a form of Northern Lights.
"It's the weirdest thing. It may be a celestial object behaving strangely. It could be an entirely new natural phenomenon," said Erik Tandberg of the Norwegian Space Centre.
"Or it could be an exploding missile. The spiral suggests it went off course, andduhing fuel could account for the blue light."
The Russians are thought to have held military exercises over the nearby White Sea on Tuesday night, but a spokesman for teh Russian military insisted there was no connection, saying: "This light was not caused by us."
"People described it as violent, beautiful and frightening," said meteorological consultant Trond Robertsen. "Of course, some say it's a portal or UFOs."
Nick Pope, former UFO analyst for the Ministry of Defence, was perplexed.
"It seems to go against the laws of physics," he said.