This January 2018 image shows the Northern Lights over southern Iceland.
Photo by Owen Humphreys/PA Images via Getty Images

This light phenomenon has some pretty cool physics behind it.

Jess McHugh
February 15, 2018

The Northern Lights, a natural phenomenon causing a gorgeous display of colors in the night sky, has so captivated people around the world that many will travel thousands of miles just to catch a glimpse in real life.

Travelers will plan a trip to Iceland or northern Canada around the time of year they're mostly likely to see the lights. One hotel in Finland even has an “Aurora Borealis monitor” on retainer, whose job it is to track when guests are most likely to see the light show.

Now physicists have a greater understanding behind what causes a very specific kind of lights, called “pulsating auroras,” thanks to new research published in Nature. Unlike Northern and Southern lights (Aurora Borealis and Aurora Australis, respectively) which appear as a seemingly unmoving displays of light, pulsating auroras grow brighter and dimmer, appearing to flicker.

“They are characterized by auroral brightening from dusk to midnight, followed by violent motions of distinct auroral arcs that eventually break up, and emerge as diffuse, pulsating auroral patches at dawn,” lead author Satoshi Kasahara wrote.

Pulsating auroras are caused by “chorus waves,” or when shifts in currents of charged particles cause electrons to scatter. These waves are thought to be caused by changes in the magnetic field.

Given the blinking movement of pulsating auroras, they can often be harder to spot, though some lucky residents in Canada were able to see one at the Pas, in Manitoba in 2017. Unlike other types of auroras, these often occur closer to the equator than to the poles, according to Science Alert, and scientists from the recently published report are still tracking their movement.

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