Nov. 29, 2012 at 5:33 PM ET
Chinese skywatchers marveled this month over mysterious rays of light in the night sky, and now sharp-eyed analysts are saying those UFO sightings were sparked by a European Ariane 5 rocket that launched two telecommunication satellites from French Guiana.
Amateur astronomers in China's Sichuan and Yunnan provinces reported seeing the weird phenomenon on Nov. 11. They watched as a luminous object moved through the heavens, shimmering with rays or rings of light. The reports made a splash on Chinese news websites such as Sina.com, as well as the Astronomy.com.cn discussion forum.
"It is certainly a UFO," one forum poster wrote in Chinese. Another wrote that the UFO was a "blessing from another planet." (I couldn't determine how that comment was meant, because my machine-translation software doesn't have a sarcasm filter.)
For a while, Chinese experts speculated that the object might have been a comet — but skywatchers soon figured out that the sightings occurred less than an hour after Arianespace sent the Eutelsat 21B and Star One C3 satellites into orbit (from the European Space Agency's South American spaceport, where it was still Nov. 10).
"The detailed analysis of the height of the UFO and the timing of observation leads me to conclude that this was the ESC-A upper stage, 30 minutes after all the fuel leaked out via passification," a Hong Kong observer known as Galactic Penguin SST reported last week on the NASASpaceflight.com forum.
Today, Want China Times said that the Beijing UFO Research Society has reached a similar conclusion.
"The 'rays' were most likely the rocket jettisoning boosters or other parts and entering low Earth orbit after being launched 30 minutes previously," the Taiwan-based online publication reported. It's also possible that the swirls of light came from fuel or vapor emanating from the upper stage. Such explanations are consistent with a host of other rocket-related UFO sightings over the years, including Russian rocket stages that have been spotted over the Middle East and Scandinavia.
Just for fun, here are a few more such cases from the UFO files:
Alan Boyle is NBCNews.com's science editor. Connect with the Cosmic Log community by "liking" the log's Facebook page, following @b0yle on Twitter and adding the Cosmic Log page to your Google+ presence. To keep up with Cosmic Log as well as NBCNews.com's other stories about science and space, sign up for the Tech & Science newsletter, delivered to your email in-box every weekday. You can also check out "The Case for Pluto," my book about the controversial dwarf planet and the search for new worlds.