A video showing what appears to be a UFO whizzing past a commercial jet has been creating a stir on the Web.
Footage captured by a startled-sounding passenger seemingly shows a white bowl-shaped object flying over Seoul, South Korea, at high speed.
At first the object keeps pace with the aeroplane, before suddenly disappearing out of shot as the passenger tries to zoom in for a closer look.
Later in the video the mysterious shape is magnified and slowed down.
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But is the UFO sighting authentic or just a computer-generated hoax?
Whatever the explanation, the video - which has racked up almost a million views since it was posted three days ago - has divided viewers. The owner of the video has speculated that it could be a military drone.
Others humorously suggest that it is a giant frisbee or flying Mentos.
Watch the video and decide for yourself.