Amateur Photographs And Satellite Data Provide More Clues To The Mystery Of Steve

Steve & the auroral picket fence in all their glory. Robert Downie Photography via ESA

The atmospheric phenomenon known as "Steve" was first mistaken for a new jazzy type of aurorae because it looks and acts similar to the northern lights. However, it was later discovered it doesn't form in the same way. It's also a fetching shade of purple rather than the classic green. Since its discovery by citizen scientists in 2017, it has fascinated both amateurs and professionals. We do love a tough-to-crack science mystery, especially one with an uncharacteristically mundane name.

In a new paper published in the Geophysical Research Letters, scientists studied images of Steve taken from multiple locations and angles to get a better understanding of where it originates from. The images show Steve and the green aurora phenomenon nicknamed "picket fences" that often accompanies it, which helped researchers to better understand the mechanism and properties of Steve.

Steve appears to originate at an altitude between 130 and 270 kilometers (between 80 and 70 miles) while the picket fence aurora is lower in altitude, ranging from 95 to 150 kilometers (60 to 95 miles). While the two phenomena are distinct, they appear to have alignments along the same magnetic lines.

Aurorae are caused by fast-moving electrons hitting the atmosphere, exciting different atoms which then emit green, red, or violet light. Data from the European Swarm satellite places Steve around three times higher and produced instead by hot gas moving at an estimated 6 kilometers (3.7 miles) per second.

Sometimes Steve can be seen accompanied by smudges of green lines – nicknamed ‘picket fences’ owing to their appearance. Janis Smith Photography via ESA

The Alberta Aurora Chasers, who were the first to identify Steve as a new phenomenon (and name it after a joke from the movie Over The Hedge), provided images of it taken from the ground. By matching the stars in the background, the team was able to triangulate the height and exact position of Steve in the night sky.

“It is remarkable to see that originally citizen scientists of the Alberta Aurora Chasers triggered the curiosity of scientists to study Steve. I’m excited that we're able to extend our understanding of Steve using photographs taken by citizen scientists,” lead author William Archer, from the University of Calgary, said in a statement. “The Canadian government has also shown interest in Steve and has recently minted a coin featuring Steve and the picket fence.”

A full picture of what Steve actually is and how it is connected to the aurorae is slowly emerging. Steve might be mysterious for now, but it hopefully won’t stay that way for long.  

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