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\t\t\t\t\t\t03\/06\/2024<\/span> Ever since aurora chasers discovered Steve, a mysterious ribbon of purple light in the night sky, scientists have wondered whether it might have a secret twin. Now, thanks to a photographer\u2019s keen eye, and data from ESA\u2019s Swarm satellites, we may have found it.<\/p>\n<\/div>\n Steve was a sensation when scientists stumbled across it a few years ago, thanks to the eagle eyes and excellent photography of the Alberta Aurora Chasers Facebook group.<\/p>\n But its mauve hue and fleeting appearance meant it couldn\u2019t be a feature of the aurora borealis, commonly known as the northern lights, which comes in shades of green, blue and red and can last for hours. So, what could it be?<\/p>\n Fortunately, ESA\u2019s trio of magnetic-field monitoring Swarm satellites were perfectly placed to help investigate.<\/p>\n It turned out that Steve was a fast-moving stream of extremely hot gas called a sub-auroral ion drift. Or, to give Steve its full name, a strong thermal emission velocity enhancement.<\/p>\n But the mystery wasn\u2019t quite over.<\/p>\n<\/p><\/div>\n Steve makes its appearance at dusk (before midnight) when the fast-moving stream of extremely hot gases move westward. But at dawn (after midnight), we also know that there\u2019s an equivalent stream moving eastward.<\/p>\n If Steve is a visual effect of the westward stream at dusk, should we not expect something similar with the eastward stream at dawn? Could Steve perhaps have a long-lost dawn-side twin?<\/p>\n A new study from the University of Electro-Communications in Japan, the Swedish Institute of Space Physics, the Arctic University of Norway and Troms\u00f8-based photographer Gabriel Arne Hofstra, suggests we might have found it.<\/p>\n It\u2019s once again thanks to researchers and citizen scientists working together.<\/p>\n The team developed an application that collects images of the aurora\u2019s nightly dances above the Norwegian Arctic from the all-sky digital camera at the Ramfjordmoen Research Station.<\/p>\n<\/p><\/div>\n Whilst looking through its data archives, Gabriel Arne Hofstra stumbled across something peculiar, something Steve-like, in an image from 28 December 2021.<\/p>\n He said, \u201cIt 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.<\/p>\n \u201cIf we have more \u2018eyes on the sky\u2019, 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.\u201d<\/p>\n But there were key differences compared to Steve. The 1000 km-long arc appeared after midnight, so on the dawn side, and was poleward of the green aurora that could also be seen.<\/p>\n<\/p><\/div>\n While none of ESA\u2019s trio of Swarm satellites flew directly through the arc at the precise time and place observed in the all-sky image, two of satellites\u2019 electric field instruments were able to measure the conditions in the purple region before, during and after the event.<\/p>\n The data showed the hallmarks of an eastward ion flow in the purple region.<\/p>\n \u201cAs a scientist, collaborating with a photographer to uncover this new phenomenon has been a fantastic experience,\u201d says Sota Nanjo of the University of Electro-Communications.<\/p>\n \u201cOur 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.\u201d<\/p>\n<\/p><\/div>\n While digital cameras are not used scientifically, they do give great contrast between the colours of normal aurora and Steve-like visual effects.<\/p>\n Now, almost everyone has a digital camera in the palm of their hand \u2013 so as one of the biggest geomagnetic storms in living memory ripped through Earth\u2019s atmosphere on Friday 10 May 2024, it also became the world\u2019s most documented aurora event ever.<\/p>\n \u201cIt\u2019s great to see yet another example of successful citizen science,\u201d says Swarm Mission Manager, Anja Str\u00f8mme. \u201cThe combination of millions of images taken worldwide, along with data from the satellites of ESA\u2019s heliophysics observatory, like Swarm, will give us an even better understanding of how space weather affects Earth\u2019s atmosphere.\u201d<\/p>\n<\/p><\/div>\n
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\n\t\t\t\t\t\t\t\t<\/figcaption><\/figure>\nPower to the digital camera<\/h2>\n