How are auroras made? Space rocket takes a closer look at the Northern Lights

The Northern Lights, also called the Aurora Borealis, have long fascinated people around the world. They appear as vibrant ribbons of green, pink, purple, and red that seem to move and shift across dark skies.

Scientists attribute this mesmerizing sight to charged particles from the sun interacting with Earth’s magnetic field and atmosphere.

These displays have typically been seen in northern regions such as Norway, Iceland, Canada, and Alaska, and they have sometimes surprised observers farther south when solar activity ramps up.

Increased solar output toward the end of our star’s current cycle has allowed sightings in places like Texas. That has brought new urgency to research efforts aimed at understanding the precise steps behind the aurora’s appearance.

Professor Peter Delamere, from the University of Alaska Fairbanks, has led a study to explore what happens at the particle level when these lights dance in rapid, shape-shifting arcs. His recent analysis was published on November 19 in Physics of Plasmas.

Studying particles in aurora lights

Until not long ago, many details about the particle processes that produce these flickering lights remained elusive.

“The dazzling lights are extremely complicated,” Delamere explained. “There’s a lot happening in there, and there’s a lot happening in the Earth’s space environment that gives rise to what we observe.”

He explained that these processes are difficult to track.

“Understanding causality in the system is extremely difficult, because we don’t know exactly what’s happening in space that’s giving rise to the light that we observe in the aurora,” he continued. “KiNET-X was a highly successful experiment that will reveal more of the aurora’s secrets.”

KiNET-X takes flight

This project, known as the Kinetic-scale Energy and momentum Transport experiment — KiNET-X — launched on May 16, 2021, from NASA’s Wallops Flight Facility in Virginia.

The mission lifted off just before the end of a nine-day launch window and headed over the Atlantic Ocean.

One of NASA’s largest sounding rockets soared to roughly 249 miles above Earth, then released two canisters of barium thermite.

About 90 seconds later, on a downward path near 186 miles high, it released the second set of canisters near Bermuda.

Observers on the ground, as well as a NASA research aircraft, watched as the barium clouds formed. Sunlight caused the barium to transform into ionized plasma, creating conditions similar to those seen in natural auroras.

Researchers sought to see if the environment created during the rocket’s flight would help them understand the way low-energy particles from the solar wind gain the energy that powers the swirling curtains of light.

Aurora lights and Alfvén Waves

The experiment attempted to form an Alfvén wave, a type of wave found in magnetized plasmas, including the sun’s outer atmosphere and the Earth’s magnetosphere.

Plasmas consist of charged particles that can conduct electricity. When something disturbs a magnetic field inside a plasma, the resulting ripple travels through the charged environment as an Alfvén wave.

KiNET-X introduced barium into the upper atmosphere to generate such a disturbance, which then caused electric fields to align with Earth’s magnetic field.

That alignment, as expected, accelerated electrons in much the same way they are sped up in real auroras.

“We generated energized electrons,” Delamere said. “We just didn’t generate enough of them to make an aurora, but the fundamental physics associated with electron energization was present in the experiment.”

Brief encounter with barium plasma

“It showed that the barium plasma cloud coupled with, and transferred energy and momentum to, the ambient plasma for a brief moment,” Delamere said.

The result was a small beam of electrons moving along the planet’s magnetic field line. Because the total amount of energized electrons was small, no visible display formed in the sky.

Still, in data readouts, scientists identified the beam as a pattern of green, blue, and yellow pixels showing up in the experiment’s magnetic field line information.

“That’s analogous to an auroral beam of electrons,” Delamere said. This finding has given researchers a key indicator for studying those invisible steps that turn free-floating solar wind into streaks of light.

How the physics fits

“It’s a question of trying to piece together the whole picture using all of the data products and numerical simulations,” Delamere said.

Through detailed analysis, KiNET-X has helped clarify the link between solar particles, magnetic fields, and those fast-moving streams that light up the night.

Investigators can also draw on past experiments in new ways, comparing data sets to see how electrons behave under similar conditions.

The KiNET-X findings suggest that a small dose of carefully placed energy can trigger large, complex interactions in plasma.

Although the rocket mission produced only a tiny pulse of enhanced particles, the core physics may be similar to the process that unleashes dancing lights above Earth’s poles.

Aurora lights and future studies

Early results confirm that KiNET-X was successful. Researchers expect to keep analyzing the experiment’s data for fresh insights.

Many are eager to see if this approach can be adjusted or repeated to capture even more details about electron acceleration.

Scientists continue to study these brilliant illuminations from many angles. As the solar cycle progresses, the Northern Lights may appear in locations far from the poles.

Researchers hope that future missions like KiNET-X, combined with ongoing modeling, will fill more gaps in our understanding of nature’s most captivating light show.

The possibilities are wide open, and each discovery brings us closer to a full explanation of how our planet interacts with the sun’s energetic winds.

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The success of KiNET-X relied on a diverse team of researchers and students.

UAF doctoral students Matthew Blandin, Kylee Branning, and Nathan Barnes played key roles, from supporting optical operations to operating cameras and assisting with computer modeling.

Collaborators from Dartmouth College, the University of New Hampshire, and Clemson University also contributed their expertise and equipment.

The study is published in the journal Physics of Plasmas.

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