(CNN) -- It wasn't a rogue galaxy closing in on Earth or a meteor hurtling toward the ground.
It also wasn't an early visit from Santa Claus.
But all of those theories and more were suggested by puzzled callers to Norway's space center after a strange swirl of blue light -- now linked to a failed Russian missile test -- was spotted in the sky Wednesday morning.
"There were many interesting suggestions," said Pal Brekke, senior adviser at the Norwegian Space Centre in Oslo. "The spiral images were very confusing. I didn't have any clue at that point either."
The phenomenon could be seen all over Norway, with witnesses describing a swirling light filling the sky around 8 a.m. and then seeming to explode.
The Russian Defense Ministry has confirmed the Russian Navy launched a Bulava ballistic missile on the same day, but has declined to make any connection with the lights seen over Norway.
It confirmed the missile was fired from the "Dmitry Donskoi" nuclear submarine, but would not comment on the submarine's location at the time of launch.
Brekke said his center was bombarded with calls shortly after he arrived at work at 8 a.m.
He said he was stumped when the first still images arrived. But when video began rolling in, Brekke -- who said he was the center's first employee to theorize correctly -- said the moving images made more sense.
"There, you could actually see something was spiraling very quickly," he said. "Immediately, I thought this must be a rocket that had been launched.
"Typically, with rockets that fail, you will see it go out of control and start spiraling."
Brekke said a fisherman off the coast of Norway has reported seeing a yellow cylinder fall out of the sky and almost hit his boat.
Truls Lynne Hansen, the head of Troms Geophysical Observatory in northern Norway, told CNN that missile launches were a common sight in the area.
"We have seen rockets being launched from north-west Russia, and the rocket range in Kiruna in northern Sweden, and from the neighboring Andenes in northern Norway, but nothing like this," Hansen said.
In a written statement, the Russian Defense Ministry said the missile failed in the third stage of its trajectory.
"Unstable work of the engine of the [missile's] third stage was detected by the monitoring systems," the statement said. "The causes of the technical error are being established by a state commission."
In addition to the calls at the space center, the Internet lit up Wednesday with theories about the mysterious glow. Early theories included an alien visit or something related to President Obama's visit to Oslo on Thursday to collect his Nobel Peace Prize.
"I think it was clear to most people that it was not a UFO, as most people define a UFO," said Erik Tandberg, a consultant to the space center. "Of course everything is a UFO until you know what it is. But most people think about UFOs as aliens and things like that."
Hansen said a combination of circumstances made the strange light clearly visible. He attributes the blue haze to gases from the missile being lit by the sun.
"We have no sunshine here at the moment. The sun is not rising and is just below the horizon to the east. The sky was very, very clear, cold and clear and this means that gas that was released by the rocket was lit up by the sun from beneath. That was one of the reasons it was so clear," he said.
Despite the relatively mundane explanation -- at least as compared to aliens or St. Nick -- Brekke said his office has never had so much excitement in one day.
The only thing I know is that the secretary has never been running around the space center so much," he said. "It was really fun and interesting. Of course, it was nice that we actually guessed the right thing from the beginning."
CNN's Hilary Whiteman contributed to this report.