Scientists say they can explain the giant, glowing orb seen over Interior Alaska last week

A white, luminous globe seen over spruce forest with green aurora in the sky above it
Still video image of an orb of light, as seen from Fairbanks, moving across the sky before 5 AM March 29th. (Courtesy of Leslie Smallwood)

A week after a large orb of light was seen moving across the early morning Alaska sky, scientists have offered an explanation.

Fairbanks photographer Leslie Smallwood captured video of the luminous sphere on automated aurora cameras before 5 a.m. on March 29.

“It seemed like it had something that was spinning inside it when I zoomed in on it,” he said. “And it’s a small tail — whitish tail.”    

Smallwood says the foggy ball of light was far larger than a full moon and moved through the sky from the northeast to the southwest over a few minutes.

“It’s not like it shot across the sky,” he said. “It was like, taking its time.”

University of Alaska Fairbanks physics professor Mark Conde says the orb was also recorded by a UAF all-sky camera in Gakona. Speaking last week, Conde said he wasn’t sure what to attribute the phenomenon to, but he noted that the orb appeared gaseous.

“A glowing cloud of gas that was sunlit would look like that,” he said.  

Jonathan McDowell, an astronomer at the Harvard Smithsonian Center for Astrophysics in Boston, Massachusetts, says sightings of the orb in Alaska correspond with the flight of a Chinese satellite deployment rocket.

“I am very confident that what people saw was the dumping of fuel from a Chinese rocket stage,” he said. “This rocket — the Longmarch 6A or Chang Zheng 6A — was launched early on March 29 from China, placed 2 satellites in orbit and, calculating its orbital path, it passed over the Yukon area about 350 miles up at exactly the time that this glow was seen in the Alaskan sky.”  

McDowell says leftover rocket fuel was likely released into space where it froze, spread out and reflected sunlight.

“This cloud is probably hundreds of miles across, that’s why it looks so big,” he said.

As to why rotating movement and a tail were observed, McDowell says that to maintain a rocket’s orbit during the release of fuel, the space craft is put into a tumble. 

“End over end while spewing out this fuel like a garden hose, and so you’ll get this sort of moving pattern,” he said.  

McDowell says rocket fuel dumps resulting in visible spheres of light occur fairly regularly in the lower 48 and elsewhere in the world. He says a similar glowing orb viewed over a large area of northern Siberia in 2017 was attributed to exhaust from ballistic missiles during test firings.

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Dan Bross is a reporter at KUAC in Fairbanks.

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