What Causes The Northern Lights? Scientists Finally Know For Sure

https://www.npr.org/2021/06/10/ [login to see] /what-causes-the-northern-lights-scientists-finally-know-for-sure
Nothing can ruin our joy in the aurora borealis, or Northern Lights, those ribbons of blue, green and violet light that cascade from the sky. Not even knowing for sure what causes them.

Physicists have long speculated about what gives rise to this very specific light phenomenon that occurs in the Earth's polar regions.

Now they're certain.

An article published in the journal Nature Communications this week suggests that the natural light show starts when disturbances on the sun pull on Earth's magnetic field. That creates cosmic undulations known as Alfvén waves that launch electrons at high speeds into Earth's atmosphere where they create the aurora.

"It was sort of theorized that that's where the energy exchange is occurring," said Gregory Howes, associate professor of physics and astronomy at the University of Iowa. "But no one had ever come up with a definitive demonstration that the Alfvén waves actually accelerate these electrons under the appropriate conditions that you have in space above the aurora."