Alberta Sky Watchers Discover Steve: A Mysterious Purple Light In The Night Sky

Alberta sky watchers chasing the northern lights have partnered with scientists on the discovery of a curious ribbon of purplish light that everyone is calling “Steve”. In photos, “Steve” shows up as a bright purple-pink streak across the sky — a light that would often appear in photos posted to the Alberta Aurora Chasers Facebook page.

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The feature is attracting attention for its unexpected name, as well as the way it was discovered, said Eric Donovan, a professor of physics and astronomy at the University of Calgary. “We have seen it from Hudson Bay all the way over to Alaska in our data, and so it’s like someone reached in from space and drew a line with a purple magic marker across the Earth”.

Steve Caught Scientific Community’s Attention

The group’s photographers began to notice Steve a few years ago, but it wasn’t a major point of scientific interest until a talk at the University of Calgary in 2015. The group’s members approached Donovan and NASA’s Elizabeth MacDonald, who works with the agency’s citizen aurora project, Aurorasaurus, with some photos of Steve.

The group was pretty convinced they had photos of a phenomenon called a proton arc, but Donovan didn’t agree as a proton arc is not visible to the naked eye. He then started cross-referencing the locations and times of those photos with information collected by the European Space Agency’s (ESA) Swarm mission. Soon, he noted some big changes after being able to match ground sightings to data from one Swarm satellite which flew directly through Steve.

Donovan said Steve appears to be a hot stream of fast-flowing gas in the higher reaches of the atmosphere, moving at a speed of about 6 kilometres per second in a westward direction. ESA had sent electric field instruments to measure it 300km above the surface of the Earth and found the temperature of the air was 3,000C hotter inside the gas stream than outside. Plus, the velocity (6km/second) of the 25km-wide ribbon of gas was 600 times faster than the air (10m/second) on either side.

While there’s still more to be discovered about the big purple light, one thing’s confirmed, it is not an aurora as it does not stem from the interaction of solar particles with the Earth’s magnetic field.

The group decided to call this phenomenon ‘Steve’ in homage to a 2006 children’s film, Over the Hedge. In the movie, animals scared of an unknown something on the other side of a hedge decided to call it Steve. Now, there’s a push to turn this name into an acronym meaning “Strong Thermal Emission Velocity Enhancement”.

The Cause Is Yet To Be Ascertained

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While Donovan acknowledged the contribution of ground-based observations, satellites, today’s explosion of access to data and an army of citizen scientists, he still remains coy about what actually causes the phenomenon.

He said, “Now what we’re doing is trying to figure out what is exactly causing this, why the gas is moving so fast, why it’s so narrow, why it’s so long in the east-west direction and why it’s so common”. But, he added the world will have to wait for his theory, which will be published “shortly”.

For now, stargazers can see Steve with the naked eye, but chances are, it won’t be appearing as bright as it looks in these heavily processed images.