Did the mythical planet believed to be the bringer of doom on Earth just appear on the American sky?

A strange, fiery object shaped like a globe was spotted off the coast of Florida earlier this month, triggering speculations, especially among conspiracy theorists, that this was an appearance of the so-called "Planet X."

The mysterious shiny object, which seemed to be burning between the clouds, was captured on video by a certain Melissa Huffman.

"Just look at that planet beaming and shining right now, somebody tells me what it is," Huffman said, as quoted by The Daily Mail, when she posted the video of the mysterious object online.

The video has already been viewed over 95,000 times, with space enthusiasts suggesting that what was captured on camera was the hypothesised Planet X, otherwise known as "Nibiru," itself.

"It's definitely Nibiru. It's time to freak out! The makers are coming," said one person who commented on Huffman's video.

Another commenter said the mysterious apparition signals the end of times on Earth.

"Me and many folk with me have been waiting for this to show up for years. Ancient records state that once The Destroyer is visible to the world, we have 40 days to prepare," the commenter said.

This comment is consistent with conspiracy theorists' belief that Planet X, said to be circling just outside the solar system, will trigger the apocalypse.

They believe that the gravitational pull of the rogue planet have already messed up the orbits of other planets.

Nibiru will also supposedly send "plasmatic energy particles" when it enters the solar system in the near future, which will trigger catastrophic changes in Earth's climate.

The National Aeronautics and Space Administration (NASA), however, has long dismissed Planet X as an Internet hoax, and categorically said that it "does not exist."

"Nibiru and other stories about wayward planets are an internet hoax," the space agency said.

"There is no factual basis for these claims. If Nibiru or Planet X were real and headed for an encounter with the Earth in 2012, astronomers would have been tracking it for at least the past decade, and it would be visible by now to the naked eye," the NASA added.