October 17, 2022

Subauroral Green STEVE Arcs: Evidence for Low-Energy Excitation

Subauroral emissions known as STEVEs (Strong Thermal Emission Velocity Enhancements) are sometimes accompanied by green arcs containing magnetic field-aligned “picket fence” structures. In a newly published spectrum of a green picket fence arc Gillies et al. (2019, https://doi.org/10.1029/2019GL083272) showed that the visible emission in such arcs is mostly OI 557.7 nm with minimal N2+ 1N. This finding …

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Color Ratios of Subauroral (STEVE) Arcs

Abstract Photos of a spectacular optical phenomenon, nicknamed STEVE, show finely structured, purple-colored, east-west arcs spanning the sky. These purple Sub-auroral Arc Emissions are associated with Sub-Auroral Ion Drifts, often accompanied by separate green arcs frequently displaying magnetic field aligned rays suggesting charge particle excitation. Both types of these arcs and polar auroras appear in …

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‘Bad’ Weather Rewards Photographer with Stunning Graduation Photos

Canadian freelance photographer Christy Turner recently ran into a bit of good luck in the form of some “bad” weather. In the aftermath of a violent thunderstorm on the day of a graduation shoot, nature rewarded her with a spectacular backdrop of mammatus clouds … and a rainbow to boot. The story began when a colleague and friend of …

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Here’s how you can maybe, possibly see the northern lights near Calgary this weekend

There’s a few reasons why astronomy enthusiasts keep tight-lipped about their aurora borealis predictions. One, saying it’s going to happen means it won’t (or so the superstition goes). Two, sightings are notoriously hard to predict, requiring a perfect recipe of solar activity to be visible. Three, conditions can change rapidly, and no one wants to …

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Chasing Steve

For years, a group of aurora chasers across Alberta have been photographing a curious ribbon of purple and green light in their night skies. Extending for thousands of kilometres and appearing for just a few minutes to an hour at a time, these Alberta Aurora Chasers captured this celestial phenomenon in their photographs not quite …

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