Northern lights aren’t chemicals sprayed in the sky. Experts say nothing else would have that effect

If you stood outside in October hoping to watch a natural light show in the sky, you’re not alone. The northern lights were visible in multiple U.S. states.

But one social media user claimed that the phenomenon is anything but natural.

"Spray the sky all day long and no one takes any notice and say ‘its normal,’" an Oct. 11 Threads post read. "Nighttime arrives and the sky is glowing with chemicals and (everyone) is On facebook screaming about seeing the northern lights."

This post was flagged as part of Meta’s efforts to combat false news and misinformation on its News Feed. (Read more about our partnership with Meta, which owns Facebook and Instagram.)

No need to edit your Facebook photo caption from calling the phenomenon "northern lights."  Experts say manufactured chemicals could not produce lights that are as widespread and that move the way northern lights do.

The northern lights or aurora borealis are produced when electrons collide with atoms and molecules of gases like oxygen and nitrogen in the Earth’s upper atmosphere. Katrina Bossert, a space physicist who is an assistant professor at Arizona State University’s School of Earth and Space Exploration, said visible aurora — red and green — are produced because of oxygen atoms’ activity. Nitrogen molecules can produce other colors.

"There is no chemical outside of oxygen that I am aware of that could produce the long lasting auroral displays we have been seeing over the US in the distinct green and red colors," Bossert said. 

Robert Steenburgh, a space scientist at the NOAA Space Weather Prediction Center, told PolitiFact the ingredients of aurora — electrons, atoms and molecules — are "already present naturally."

Claims of chemical spraying in the sky often fall under the "chemtrails" conspiracy, which atmospheric chemists and geochemists have rejected. A 2016 study surveyed 77 scientists and all but one of them said they have not found evidence of a "secret, large-scale atmospheric spraying program." 

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Line-shaped clouds in the sky are not proof that bad actors are spraying chemicals over land; these clouds are condensation trails or contrails, which are produced by aircraft engine exhaust and primarily consists of ice crystals.

Because of a severe geomagnetic storm, many people in North America saw the Oct. 11 aurora borealis. Storms such as this make it likelier for aurora borealis to occur.

It is not unusual for the aurora borealis to be observed in the U.S. Steenburgh said the region of the aurora or the "auroral oval" expands and moves toward the equator during geomagnetic storms.

Aaron Ridley, a professor at University of Michigan’s Climate and Space Sciences and Engineering Department, said hundreds of people capture and upload photos of aurora across many countries. "There are no chemicals that could be deposited across this much space and lit up in this way," he said.

He also said that no sprayed chemical could act in the atmosphere like northern lights do; they brighten and dim. Ridley said such chemicals would move with the wind.

Some scientific rocket experiments release chemicals that can emit light, such as trimethyl aluminum, barium and strontium, said Toshi Nishimura, Boston University research associate professor who studies aurora. "Though strictly speaking, they are not aurora but airglow," he said. 

A rare NASA experiment uses sounding rockets that emit tracers to measure winds in the upper atmosphere and ionosphere. 

The trimethyl aluminum produces a whitish glow when it reacts with oxygen atoms, Bossert said, but this dissipates quickly. "The trail has a distinct look and would not be mistaken for widespread aurora," Bossert said.

We rate the claim that the northern lights are chemicals sprayed in the sky False.

RELATED: Geomagnetic storm, not a HAARP experiment, created dazzling, worldwide northern lights display