The greatest "light show" on earth - the mysterious origin of the Northern Lights is confirmed

The Northern Lights are often described as the greatest "light show" on Earth. This phenomenon, unique to high latitudes, has amazed scientists for centuries. The cause of the Northern Lights has also been speculated but has never been confirmed, until now.

According to a newly released study, a team of physicists at the University of Iowa has finally confirmed that "the most stunning auroras are produced by powerful electromagnetic waves during geomagnetic storms."

These phenomena, also known as Alfven waves, accelerate electrons toward Earth, causing the particles to create what we know as auroras.

"Measurements show that this small group of electrons is 'resonantly accelerated' by the Alfvén wave electric field, which is similar to a surfer grabbing a wave and continuously accelerating as the wave moves." Greg Howes, an associate professor in the Department of Physics and Astronomy at the University of Iowa and a co-author of the study.

In 1946, Russian physicist Lev Landau first proposed the theory of electrons "surfing" on the electric field and named it Landau damping. His theory has now been confirmed.

Recreating the Northern Lights

For decades, scientists have understood the most likely causes of the auroras. But now for the first time, they can simulate it in the Large Plasma Device (LPD) at the Laboratory for Basic Plasma Science Facility at UCLA.

Scientists used the powerful magnetic field coils on UCLA's LPD to reconstruct the Earth's magnetic field in a 20-meter-long chamber. Within this chamber, the scientists created a plasma similar to that found in space near Earth.

"We used a specially designed antenna to wave Alfvén waves up and down the machine, much like shaking a garden hose up and down quickly, and then watched the waves propagate along the hose," House said. As they began to experience electrons "surfing" along the waves, they used another specialized instrument to measure how those electrons gained energy from the waves.

Although the experiment did not reproduce the colorful shimmers we see in the sky, House said: "Our measurements in the laboratory are clearly consistent with predictions from computer simulations and mathematical calculations, demonstrating that electron surfing on Alfvén waves can accelerate electrons (to speeds of up to 45 million miles per hour, approximately 72.42 million kilometers per hour) to produce auroras."

"These experiments allow us to make key measurements that show that spatial measurements and theory do explain the main causes of auroras," said study co-author Craig Kletzing.

Many space scientists were overjoyed when they heard the news. "I couldn't be more excited! It's very rare to have a theory or model about the space environment tested through laboratory experiments," said Patrick Koehn, a scientist in NASA's Heliophysics Division. "Space is clearly too vast to be easily simulated in the laboratory."

"It will really help us better understand space weather! The electron acceleration mechanism demonstrated by this project is also at work elsewhere in the solar system, so it will be very useful in space physics. It will also be used for space weather forecasting, which NASA is very interested in." Cohen said in an email to CNN.

There's still a long way to go

Now that the theory of how auroras form has been confirmed, there's still a long way to go in predicting the intensity of each storm.

"Predicting the intensity of a specific magnetic storm based on observations of the Sun and measurements from spacecraft between the Earth and the Sun remains an open challenge," Associate Professor House said in an email.

"We have established the link to electrons surfing through Alfvén waves ten thousand miles above the Earth's surface, now we have to learn how to predict the strength of Alfvén waves from spacecraft observations," he added.