Citizens with a knack for science chasing the northern lights came upon a new feature of the aurora borealis. Presented as a purple streak of light in the night sky, the phenomenon was given an unusual name on social media: Steve.
Photos of the "strange ribbon of purple light," captured both from the ground and by the Swarm satellite, revealed the atmospheric phenomenon's secret, uncovering it's not in fact an aurora.
What Steve Is And How It Got Its Name
After making an appearance on the Alberta Aurora Chasers, a Facebook group for aurora borealis enthusiasts, the newly discovered feature was analyzed by Professor Eric Donovan from the University of Calgary.
Just like the Aurorasaurus citizen science project, the Facebook group connects people passionate about the aurora borealis with real-life scientists, and shares photos and observations regarding this beautiful phenomenon.
Group members had met Donovan at a recent talk, and so the scientist was introduced to the purple streak of light in the group's photos, where it was described by the members as a "proton arc." However, knowing proton auroras are never visible and therefore can't be photographed, Donovan suspected the light ribbon has to be something else.
Intrigued by the new discovery, he compared the social media photos with images taken by the Swarm mission and an entire network of all-sky cameras. He was then able to match the ground sightings to data from one of the three Swarm satellites sent to fly through the mysterious light show.
Testing showed the phenomenon doesn't stem from the interaction of solar particles with the Earth's magnetic field, but instead appears to be a hot stream of fast-flowing gas in the higher reaches of the atmosphere.
As the Facebook community didn't initially know what their discovery was, they resolved to name the phenomenon "Steve" — in homage to how the characters in the movie Over the Hedge call something they have not seen before — and even came up with a scientific acronym to account for the name they found so endearing: Sudden Thermal Emission from Velocity Enhancement.
Swarm Satellite Shows Steve's Temperature And Velocity
According to an ESA news release, the field instrument sent to measure Steve 190 miles above our planet's surface found the gas stream had an inside air temperature and velocity higher than on the outside.
Swarm measurements revealed the purple gas ribbon was 25 kilometers wide (or about 15.5 miles in diameter), with an inside temperature 3,000 Celsius degrees (or about 5,400 Fahrenheit) hotter than on the outside.
In addition, the gas stream was found to be "flowing westward at about 6 km/s [13,421 miles per hour] compared to a speed of about 10 m/s [22 miles per hour] on either side of the ribbon," said Donovan. That's nearly 600 times faster than the air on both sides.
"It turns out that Steve is actually remarkably common, but we hadn't noticed it before," added Donovan, who acknowledges the important role played in this discovery by "today's explosion of access to data and an army of citizen scientists joining forces to document it."