An airplane passenger videoed a mysterious oval white object flying over Seoul, South Korea, April 7. The video has been lighting up the Internet since, and of course many people are offering extraterrestrial explanations.
As is de rigueur these days, the UFO clip was uploaded to YouTube, where it has been viewed millions of times. Some comments say it's clearly an extraterrestrial spacecraft; others insist it's a fake. Still others say it's neither but instead is a real object — such as a plastic bag in the wind, a parachute seen from above, or a drop of water on the window — that simply looks strange from that angle.
Aside from the anonymity of the cameraman, the video raises some red flags about its authenticity. For one thing, the video is not complete; it has been purposely edited to leave some information out. We know this because it begins in progress, with the UFO already well in frame, in the lower right-hand corner. The video camera didn't suddenly turn on to capture that scene; there must be at least some video that was recorded the first few seconds of the camera being turned on or the cameraman pointing the camera out the window. This type of selective editing is common among UFO hoax videos.
There's also the fact that the cameraman waits almost seven seconds before he mentions the UFO to his companion. It's clearly present, and it would be hard to keep your reaction to yourself if you were watching while you were videotaping.
Perhaps most strange, even though he clearly spots the UFO, the cameraman makes no effort to follow the object after it zooms up and out of frame; instead he videotapes more or less the same area of sky for the remaining 10 seconds of the clip. [Video of UFOs Swarming Over Las Vegas Is for the Birds]
While these internal clues suggest something's not right with the video, the question remains: Was it a real object? Some of the most popular explanations don't fit the facts. A plastic bag, for example, would be unlikely to reach that altitude (and would not appear that large), and a parachute could not move as seen in the video.
The best earthly explanation for the UFO is that it's a droplet of water on the outside of the window being pushed up by airflow coming from under the fuselage. This would explain why the UFO is out of focus: because it's close to the lens. It would not, however, explain why the UFO appears to maintain a constant shape. Droplets of water, especially when subjected to high pressure, tend to deform and leave droplet trails as they move across a smooth surface. This one does not.
Then there's the fact that the light and shadow pattern on the blurry white object doesn't change as it moves. It's almost as if the UFO intentionally maintained exactly the same angle toward the camera the whole time — not impossible, but highly suspicious.
Absent a terrestrial explanation, we turned to Derek Serra, a Hollywood visual effects artist who has analyzed previous UFO videos. Serra said he finds several elements in this South Korean UFO video that "scream fake," including that "the motion blur was done by an amateur," he told Life's Little Mysteries. "When the camera zooms in a bit, and when the UFO flies off screen, you can seen 'ghosting' of the image. Actual motion blur of real, three-dimensional objects creates a smooth gradient, not a stuttered ghosting like we see in this video. It is something we make sure we do right when working on shots for TV and film."
Though all signs point to a hoax, it's possible that alien spacecraft technology is so advanced that the spacecraft have the sneaky ability to appear on our cameras looking exactly like faked video images.
Live Science newsletter
Stay up to date on the latest science news by signing up for our Essentials newsletter.