"Auroras are nature's most special light show: when charged particles from the sun hit our atmosphere, they can generate bright colors that dance across the night sky near the Earth's poles. Auroras can come in various forms, including bands, rays, patches and more. But why auroras form these patterns is less clear. Now, researchers say they've identified the battery that powers at least one kind of auroraaurora arcs."
"In a new study published in Nature Communications, scientists describe how charged particles in our atmosphere become powered up by Alfven waves, a special kind of plasma wave that travels along Earth's magnetic lines and acts like a space battery, according to NASA. Auroral arcs form when fast-moving electrons, juiced by Alfven waves, hit atoms in our atmosphere, releasing light in towering bands."
Alfven waves, a type of plasma wave that travels along Earth's magnetic field lines, act like a space battery and energize charged particles in the upper atmosphere. Fast-moving electrons accelerated by these waves collide with atmospheric atoms and emit light, producing auroral arcs—long, bright bands that appear near the poles. Auroras also take forms such as rays and patches. Coordinated measurements from military and NASA spacecraft in 2015 provided multiple viewpoints and sufficient temporal coverage to trace electron acceleration to Alfven waves, clarifying the mechanism that powers at least one kind of auroral display.
Read at www.scientificamerican.com
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