An eerie ghost city recently appeared floating in the clouds above the Chinese cities of Jiangxi and Foshan, with thousands of eyewitness accounts, reports The Telegraph. The supernatural-seeming event was even caught on film. Bizarre images show a shadowy cityscape sitting atop clouds, skyscrapers literally poking the sky.

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Of course, the event quickly became fodder for those with active imaginations. A city of the gods? A haunted city? (Just in time for Halloween.) A glitch in "The Matrix"? The spectral manifestation of a parallel universe?

According to scientists, none of the above. Although the images and eyewitness accounts are rather spooky and relatively lucid, the peculiar cloud city was most likely caused by a rare kind of light-bending mirage called Fata Morgana.

Aptly named after Morgan le Fay, a powerful enchantress from the tales of King Arthur, Fata Morgana mirages are caused by the refraction of light that happens when different layers of adjacent atmosphere experience different temperatures, and thus different densities. Basically, when light hits one of these atmospheric boundaries, it bends. Since our brains process light entering our eyes as if that light had traveled in a straight path, we end up seeing things in the sky that are not actually there. In this case, the image of the cityscape in the sky was probably just a reflection of actual cities on the ground.

It's an eye-rubbing effect, but nothing more than a mirage. Interestingly, Fata Morgana illusions may be to blame for many strange historical tales, such as floating castles occasionally witnessed by sailors, and possibly even the Flying Dutchman, a specter ship said to drift through the North Sea.

Despite this totally rational explanation, however, there are plenty of observers who remain spooked and unconvinced. Among the zanier theories out there is the idea that the city was an attempt by NASA to simulate the second coming of Christ. Conspiracy theorists have even given this nefarious project a name: Project Blue Beam. It is supposed to be part of an elaborate plan by NASA to establish a new world order. Yes, some people actually believe this.

Regardless, the floating city is certainly one of the cooler examples of a Fata Morgana mirage ever caught on film. Imagine witnessing this image in the sky above you. What would be your reaction?

Bryan Nelson ( @@brynelson ) writes about everything from environmental problems here on Earth to big questions in space.

Mysterious floating city appears in sky above China
Scientists say the floating city was just a mirage, but conspiracy theorists have their own ideas.