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Clashing magnetic fields blast solar winds

northern lights

Scientist say they know what causes solar winds, which gust through the solar system, interact with earth's magnetic bubble and cause the northern and southern lights (Source: iStockphoto)

The solar wind paints earth's skies with auroras and can disrupt power grids. But just how the streams of electrically charged particles flow out of the sun has been a mystery until now.

Like most phenomena associated with stars, the process is violent, international scientists have discovered.

Pockets of hot gases on the sun's surface, which pool around bright knots of magnetic activity, spurt out into space when the sun's snarling, snaking magnetic fields collide.

"[The phenomenon] has been debated for many years," says Professor Louise Harra, a University College London researcher who this week unveiled the sun's secret at a Royal Astronomical Society meeting in Belfast.

Harra planned to show images from the orbiting Hinode spacecraft showing magnetic fields linking two bright spots on the sun.

The spots are nearly 500 million kilometres apart, a distance equivalent to 40 earths placed side by side.

When the magnetic fields smashed into each other, charged gases flew out in all directions, forming the solar wind.

"It is fantastic to finally be able to pinpoint the source," Harra says, adding that the next step is to figure out how the wind is transported through the solar system.

The solar wind permeates the solar system, defining its shape and scope, as it blasts along at 200 kilometres per second on the slow days.

During snappier binges, strong gusts blasting into earth's magnetic bubble can have a myriad ramifications from the beautiful and benign aurora above earth's poles to the shutdown of power and communications systems on the planet.

Fountains in space

At the same meeting, astronomers also discussed the forces behind volcanic-type explosions of gas from the sun's atmosphere.

These so-called fountains are places of increased pressure at the base of the sun's magnetic fields, says Dr Michelle Murray, also from University College London.

As the magnetic fields rearrange themselves, the pressure periodically tails off, allowing the gases to fall back toward the sun's surface.

Computer simulations based on Hinode data show that when a new section of magnetic field pushes through the solar surface, it generates a continual cycle of fountains.

"New magnetic fields are constantly emerging across the whole of the solar surface, so our results can explain a whole multitude of fountains that have been observed," Murray says.

Tags: astronomy-space, physics, phenomena