A UFO was seen by millions of people hovering over the opening ceremonies at the London Olympics earlier this week. The glowing craft could be seen during the huge fireworks display at the end. Most people missed (or ignored) it, but one eagle-eyed TV viewer was convinced he’d seen something mysterious.

He posted a video of it to YouTube and it went viral, stirring controversy around the Web (watch the video at the bottom of this post). Enhancing the video, some saw a dome atop a disc-shaped spacecraft; others thought it might be a blimp at first, but realized it wasn’t because, as one poster asked, “Why would a company spend millions getting a blimp in the air and then not put advertising on it?”

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This is not the first time that UFOs have been sighted flying over or near public events. Though extraterrestrials have been shy about landing on the proverbial White house lawn, they have (allegedly) appeared above huge crowds many times.

For example, in December 2011 an unidentified craft was spotted hovering high above an anti-government protest in Moscow's Bolotnaya Square in Russia. It was strangely silent, and clearly not a helicopter. The UFO was caught on video, and had some protesters wondering if they were being watched by aliens. Later analysis showed that the UFO was in fact a camera drone used by the news media.

Then there was the case of UFOs sighted over a Scottsdale, Ariz., high school football game in October 2011. The four bright lights seemed to move slowly in the sky, sometimes blinking randomly and lasted for about a minute and a half. Predictably, a video of it was posted it to YouTube, where within days it became one of the top stories on Yahoo News and sparked "a national mystery.”

I investigated the case and found that the UFOs were actually flares attached to skydivers putting on a show several miles away.

So there’s plenty of precedent for Unidentified Flying Objects being seen by thousands and equal precedent to believe that they're probably not extraterrestrial in origin, but instead have an earthly explanation.

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In this case, the mystery was finally put to rest after a few days. It was the Goodyear blimp, which provided aerial coverage of the Olympic festivities. Skeptical investigator Robert Sheaffer, who analyzed the case on his Bad UFOs blog, noted that the UFO had already been identified by many people: It was the “Spirit of Europe II,” a 130-foot-long blimp which — as per Olympic rules — had the Goodyear logo removed.

Sheaffer compared the image from the video to photos taken from the website of the Goodyear Blimp: “I think those people know their own Blimp when they see it,” Sheaffer concluded. “The resemblance between this object, and the unknown object in the video is obvious. Case Closed: The object was the Goodyear Blimp.”

But, as with most UFO explanations, some true believers insisted that it was an unknown craft, saying for example that the image does not seem to be blimp-shaped. One commenter admitted that the object “looks blimpish,” but then (incorrectly) stated that “blimps don't glow” (in fact Spirit of Europe II is illuminated). It’s true that many blimps do not glow, except when they are brightly lit from below by a world-class fireworks display.

Indeed, as Examiner blogger Tom Rose noted, “Ardent believers, some with impressive video analytical skills, are using the web to make their case that the sighting was authentic.” For example one person put up a YouTube video analysis which he believes clearly makes the case that “the object filmed During the Olympic opening ceremony is not a blimp or drone… i am confirming this as a genuine UFO sighting.” (He did not explain where the Goodyear blimp, which is known to have been in the same location at the same time as the ‘mysterious UFO’, actually was, if they were indeed two different craft.)

As the Olympic UFO shows, it’s very easy to create a “UFO report”: All you need is one or two people who see something they can’t explain, aided by misinformation and incorrect assumptions.

Image Courtesy of YouTube