The science behind why some auroras have such surprising wave patterns
Auroras, twinkling bands of light that emerge from the night sky near Earth’s poles, may follow patterns known as arcs.
Green auroral arc extended into the sky over northwestern Canada in 2019
The auroras are nature’s most special light show: When charged particles from the Sun hit our atmosphere, they can produce bright colors that dance across the night sky near Earth’s poles. aurora can come various formsWhich includes bands, rays, patches and more.
But why auroras create these patterns is less clear. Now, researchers say they have identified the “battery” that powers at least one type of aurora—aurora arcs.
A green auroral arch is visible above clouds in this photo taken by an astronaut aboard the International Space Station in 2014.
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In a new study published In nature communicationScientists explain how charged particles in our atmosphere are powered by “Alfvén waves”, a special type 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 driven by Alfvén waves collide with atoms in our atmosphere, releasing light in the higher bands.
A panorama of the Northern Lights in the northern, eastern and southern sky near Churchill, Manitoba on February 27, 2025
The discovery was somewhat of a stroke of luck, made possible by synchronized measurements of the auroral arc by both military and NASA spacecraft in 2015. “These combined observations provide separate perspectives long enough to reveal more about the conditions in space that helped form the arc,” NASA said in a statement.
Although the Sun’s latest activity cycle has likely already peaked, there are still abundant aurora sightings to be expected in 2026, with the Northern Hemisphere season lasting until March.
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