Steve was first identified a few years ago by the Alberta Aurora Chasers Facebook group. Its mauve hue and fleeting appearance differentiated it from the aurora borealis, which appears in green, blue, and red and lasts for hours. Steve is a fast-moving stream of extremely hot gas called a sub-auroral ion drift, or a strong thermal emission velocity enhancement.
Steve appears at dusk when the fast-moving stream of hot gases moves westward. Scientists also know of an equivalent stream moving eastward at dawn. This raised the question of whether there might be a similar visual effect on the dawn side.
A new study from the University of Electro-Communications in Japan, the Swedish Institute of Space Physics, the Arctic University of Norway, and Tromso-based photographer Gabriel Arne Hofstra suggests we might have found Steve's twin. Researchers and citizen scientists collaborated to develop an application that collects images of the aurora above the Norwegian Arctic from the all-sky digital camera at the Ramfjordmoen Research Station.
Gabriel Arne Hofstra discovered something Steve-like in an image from 28 December 2021. He said, "It has been amazing to have contributed to new science and help scientists uncover this phenomena. To me, it proves that we citizens can contribute to understanding the world we live in by collaborating with scientists. If we have more 'eyes on the sky,' we can help unravel its mysteries. I really hope that the recent great geomagnetic storm and spectacular skies has encouraged more people to be interested in space physics and contribute to our scientific understanding of our world."
The arc appeared after midnight, on the dawn side, and was poleward of the green aurora. While none of ESA's Swarm satellites flew directly through the arc at the observed time and place, two satellites' electric field instruments measured the conditions in the purple region before, during, and after the event. The data indicated an eastward ion flow.
"As a scientist, collaborating with a photographer to uncover this new phenomenon has been a fantastic experience," said Sota Nanjo of the University of Electro-Communications.
"Our findings not only open new avenues in auroral physics, but also underscore the importance of continuous collaboration between scientists and photographers. Such efforts are particularly crucial in the coming years as solar activity approaches its peak, when we may encounter extraordinary phenomena."
Digital cameras, while not used scientifically, provide great contrast between the colors of normal aurora and Steve-like effects. With digital cameras widely available, the geomagnetic storm on 10 May 2024 became the world's most documented aurora event.
"It's great to see yet another example of successful citizen science," said Swarm Mission Manager, Anja Stromme.
"The combination of millions of images taken worldwide, along with data from the satellites of ESA's heliophysics observatory, like Swarm, will give us an even better understanding of how space weather affects Earth's atmosphere."
Related Links
Swarm at ESA
Solar Science News at SpaceDaily
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