Citizen scientists have helped explain a spectacular form of light which burns through the sky in a 3000° celsius arc:
It’s been documented before. The group called it a “proton arc”, which is where things get a little complicated.
Donovan knew proton aurora (note, not “arc”) were not visible, so the group came up with a new name for it – “Steve”.
You might recognise that from the movie “Over the Hedge”, where the forest animals, who have never seen an urban hedge, decide to call it “Steve”.
Donovan kept in touch with the group and eventually, a Steve sighting date coincided with the overpass of one of the European Space Agency’s three Swarm satellites.
The satellite certainly got to know Steve.
“The temperature 300 km above Earth’s surface jumped by 3000°C and the data revealed a 25 km-wide ribbon of gas flowing westwards at about 6 km/s compared to a speed of about 10 m/s either side of the ribbon,” Donovan said.
Of course, the phenomenon has been occurring since forever. But Donovan said that just 20 years ago, there was only one sky imager in North America which could be coordinated with sightings.
“Back then we would be lucky if we got one photograph a night of the aurora taken from the ground that coincides with an observation from a satellite,” he said.
“Now we have many more all-sky imagers and satellite missions like Swarm so we get more than 100 a night.”
There’s now a whole “Gallery of Steve” full of spectacular pictures of the phenomenon:
And as for the “aurora” versus “arc” discussion, the Aurora Australis Tasmania group has been snapping them for years:
— Dr. Tamitha Skov (@TamithaSkov) January 1, 2017
Sonnemann says the group reported only one “out of every 10 or 20 aurorae” showed the arc.
“They seem to come at the end of a display, when the event is waning,” she said. “They start out as you have pictured but then they elongate dissipate, pass through the Zenith and end up all the way to the opposite horizon. Very special.”
You can see more incredible aurora pics from the Tasmanian group here.
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