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

Still video image of an orb of light, seen from Fairbanks, moving across the sky before 5 a.m. on March 29. (Courtesy of Leslie Smallwood)

A week after a large orb of light was seen moving across Alaska’s early morning sky, scientists have come up with an explanation.

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

“There seemed to be something spinning inside when I zoomed in on it,” he said. “And it’s a little tail – a whitish tail.”

Smallwood says the hazy ball of light was much larger than a full moon and moved across the sky from northeast to southwest in minutes.

“It’s not like it crossed the sky,” he said. “It was like taking your time.”

Mark Conde, a physics professor at the University of Alaska Fairbanks, said the orb was also recorded by a UAF all-sky camera in Gakona. Speaking last week, Condé said he was unsure what to attribute the phenomenon to, but noted that the orb appeared to be gaseous.

“A cloud of glowing gas lit by the sun would look like this,” he said.

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

“I’m very confident that what people saw was the fuel spill 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 region at about 350 miles exactly when this glow was seen in the Alaskan sky.

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

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

As to why spinning motion and tailing were observed, McDowell says that to maintain a rocket’s orbit while fuel is being released, the spacecraft is put into free fall.

“End to end while spitting out that fuel like a garden hose, and you’ll get that kind of movement that way,” he said.

McDowell says rocket fuel spills resulting in visible spheres of light occur fairly regularly in the Lower 48 and elsewhere around the world. He says a similar glowing orb seen over much of northern Siberia in 2017 was attributed to ballistic missile exhaust during test firings.

Betty K. Park