No, this isn’t the hoax or photo trick. Thousands of people in China this week reported seeing a large “floating city” in the sky that actually turned out to be a Fata Morgana, which is a rare type of mirage.

gigglesinclick, giggles

This particular mirage is absolutely massive and really does look like a giant city that’s floating in the clouds.

“[Mirages] are real phenomena of atmospheric optics, caused by strong ray-bending in layers with steep thermal gradients,” the page explains. “Because mirages are real physical phenomena, they can be photographed.”

These mirages occur whenever the sun heats up a layer of the atmosphere even as the layer below it remains at a cooler temperature. This causes light travelling through the atmosphere to get refracted and creates the illusion of objects in the sky like the giant city we see in the video.