Everything you’ve ever wanted to know about the Northern Lights

The Northern Lights over  Valvika, Nordland, Norway (Photo: Trond Kristiansen)

The Northern Lights over Valvika, Nordland, Norway (Photo: Trond Kristiansen)

Did you know that scientists are launching rockets to the Northern Lights to better understand the phenomenon? That the tail of the Northern Lights starts 150 million kilometers out in space? That the color of the lights depends on a particle’s speed? Norwegian solar physicist Pål Brekke knows this and more. At TEDxArendal, Brekke gives a crash course on the physics of the light phenomenon, explaining how  these dazzling displays work — from space to our skies.

A photo taken from one of Brekke's trips to view the Northen Lights. (Credit: Pål Brekke)

A photo taken from one of Brekke’s trips to view the Northen Lights. (Credit: Pål Brekke)

The Aurora Borealis we all know and love starts in space, Brekke says. Specifically, on the sun. You see, the sun is full of energy, and a bit of this energy action comes in the form of sunspots, which — thanks to really powerful magnetic fields — create loops of solar gas, some loops 50 times larger than the Earth and all chock full of energy.

“Enormous amounts of energy are released in these loops,” says Brekke, “and sometimes these loops can snap and what happens then is that the gas will be thrown out into space. And sometimes these gas clouds are directed toward the Earth.”

Hot gas clings to magnetic fields in sun spot regions on the sun (Credit: NASA)

Hot gas clings to magnetic fields in sun spot regions on the sun (Credit: NASA)

Gas clouds moving toward Earth (Credit: NASA)

Gas clouds moving toward Earth (Credit: NASA)

This gas moves toward the Earth at breakneck speeds, says Brekke, up to 8 million kilometers per hour, and then days later, reach the Earth’s atmosphere and “we get some interesting effects.”

Example one — the Aurora Borealis. When these hurtling gas storms come into contact with the Earth’s magnetic field — the magnetosphere — some particles “are ejected back along the magnetic field lines and end up in the polar regions,” Brekke says, “and then they collide with the atmosphere and we get polar lights.”

How? Physics. As these streams of particles move into the polar regions, they begin to collide with everything that makes up the air around us. “They will actually transfer some energy to each of those atoms and molecules,” Brekke says. “And then they will start glowing in the dark. Some atoms will emit red light, some green light, some purple and so on, depending on the speed of the particle hitting them.”

An animation of particles forming the Northern Lights (Credit: NASA)

An animation of particles forming the Northern Lights (Credit: NASA)

The glow-in-the-dark effect is a consequence of energy transfer, Brekke says. “When a particle hits an atom, it transfers some energy into it. The outermost electron has to move out to different orbits, and it doesn’t like to be there, so it tries to get back to where it belongs, and to do that, it has to send out energy in the form of light — a photon. The color of the photon is dependent on the energy levels between those atom orbits.”

Real time video of the Northern Lights in Norway. (Credit: Pål Brekke)

Real time video of the Northern Lights in Norway. (Credit: Pål Brekke)

To truly appreciate the complexity of the Lights, you have to see them, says Brekkie, who chases the Aurora Borealis himself.

To learn more (including breathtaking video of the Northern Lights from space), watch Brekke’s whole talk below:

Why we like this talk:
The speaker is an accredited physicist who gives a fascinating overview of a beloved natural phenomenon — the Northern Lights. His idea — that the Northern Lights are not just beautiful, but provide a very special link between the sun and the Earth, is an interesting one, and is supported by his deep dive into recent research as well as emerging technology for capturing and understanding this phenomenon better.

1 Comment

  1. It was a great pleasure to talk at TEDxArendal. For those who want to learn more about the Northern Lights we have made an award-winning documentary now available on DVD in eight languages. Here is more info and the trailer:

    https://vimeo.com/87472898

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