Surfing Particles Can Supercharge Northern Lights

In a conversation from 2021, Ira and a researcher discuss how the physics of plasma, particles, and the Earth’s magnetic field combine in dazzling displays of aurora.

For thousands of years, humans have been observing and studying the Northern lights, aurora borealis, and their southern hemisphere counterpart, aurora australis. The simplest explanation for how these aurora form has been unchanged for decades: Charged particles, energized by the sun, bounce off the Earth’s protective magnetic field and create flashes of light in the process.

But for a long time, scientists have known it was more complicated than that. What exactly gives those incoming particles the energy they need to create the patterns we see? And why are some aurora more dramatic and distinct, while others are subtle and hazier?

Aurora researcher Jim Schroeder explains new work published in Nature Communications that suggests that in more vivid aurora, electrons may “surf” waves of energy from space into our atmosphere. The waves, called Alfvén waves, are a side effect of the solar wind warping the Earth’s magnetic field. Schroeder explains the weird physics of our aurora, and what we could learn about other objects in the universe as a result. 

 Transcript for this segment is available on sciencefriday.com.

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