On November 5, 2023, during the day, a large Coronal Mass Ejection (CME) struck the Earth. This event triggered a significant Northern Lights display over Europe. As North America transitioned into the evening hours, many hoped for a strong solar storm. Unfortunately, as we have witnessed time and time again, the early impact caused space weather conditions to weaken as we moved into the overnight hours. Geomagnetic storming conditions continued, but they were not sufficient to ignite the auroras as far south as Central Illinois.
I headed out as the sun set, and the sky was dark enough to capture a good photo of the night sky. As I aimed my camera and took the photo, I captured a bright red glow in the sky. My first impression was that it was the Northern Lights. In reality, it was a SAR Arc.
What is a SAR Arc? SAR is an abbreviation for Stable Auroral Red Arcs. Although SAR Arcs are not the Aurora itself, they form during geomagnetic storms. They occur when solar particles interact with oxygen in the ionosphere, heating the oxygen and generating a stable red glow above our heads, hence the name “Stable Auroral Red.” These are not visible with the naked eye and a long exposure photo is the best way to capture them.
Regardless of their level of fame, SAR Arcs are another cool part of geomagnetic storms. They add a touch of mystique to our understanding of the night sky and remind us that there’s always something new to discover in the great cosmic tapestry above and another reason to go out and to look up at the sky above!
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