NASA scientists help identify what powers this type of aurora
When charged particles from space collide with Earth’s upper atmosphere, they form a colored pattern across the sky. This phenomenon is called an aurora.
There is, however, a type of aurora called auroral arcs. When observing auroral arcs from the ground, they look like glowing curtains of light sweeping across the night sky. From space, they look like a thin green line or arc slicing across the atmosphere.
Auroral arcs are formed when high-energy electrons in space slam into atoms in Earth’s upper atmosphere. This process releases a characteristic display of natural light. Essentially, they are powered by electric fields in space. But what powers that electric field? A team of researchers may have finally solved the mystery.
The researchers’ findings suggest that auroral arcs are powered by a type of space waves called Alfvén waves. Alfvén waves travel along Earth’s magnetic field lines. The scientists got their results by looking at a simultaneous observation of an auroral arc in April 2015. The observation was made by three instruments: NASA’s Van Allen Probes, the U.S. military’s Defense Meteorological Satellite Program F19 spacecraft, and ground-based cameras for NASA’s THEMIS (Time History of Events and Macroscale Interactions during Substorms) mission.
The combined observation of the three instruments provided an advantage. The scientists were able to see different viewpoints of the same event for a long enough period of time. This helped reveal more about the space conditions that helped form the auroral arc.
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