Secrets of the solar wind revealed: Stunning Nasa video

Written by Mark Prigg

It looks like a calm, orderly lab experiment at first glance. But in fact this incredible video shows the solar wind as it leave’s the sun’s surface – in stark contrast to the gusty and turbulent wind as it approaches Earth.

Ever since the 1950s discovery of the solar wind – the constant flow of charged particles from the sun – there’s been a stark disconnect between this outpouring and the sun itself. Near the sun where it originates, this wind is structured in distinct rays, much like a child’s simple drawing of the sun, researchers found.

solar wind

However, the details of the transition from defined rays in the corona, the sun’s upper atmosphere, to the solar wind have been, until now, a mystery. Using NASA’s Solar Terrestrial Relations Observatory, or STEREO, scientists have for the first time imaged the edge of the sun.

‘Now we have a global picture of solar wind evolution,’ said Nicholeen Viall, a co-author of the paper and a solar scientist at NASA’s Goddard Space Flight Center in Greenbelt, Maryland. ‘This is really going to change our understanding of how the space environment develops.’

The research,  published in The Astrophysical Journal, shows for the first time the details of the transition from defined rays in the corona, the sun’s upper atmosphere, to the solar wind.

What is solar wind?

The sun and its atmosphere are made of plasma – a mix of positively and negatively charged particles which have separated at extremely high temperatures, that both carries and travels along magnetic field lines.

Material from the corona streams out into space, filling the solar system with the solar wind. But scientists found that as the plasma travels further away from the sun, things change: The sun begins to lose magnetic control, forming the boundary that defines the outer corona – the very edge of the sun.

Both near Earth and far past Pluto, our space environment is dominated by activity on the sun.

The sun and its atmosphere are made of plasma – a mix of positively and negatively charged particles which have separated at extremely high temperatures, that both carries and travels along magnetic field lines. Material from the corona streams out into space, filling the solar system with the solar wind.

But scientists found that as the plasma travels further away from the sun, things change: The sun begins to lose magnetic control, forming the boundary that defines the outer corona – the very edge of the sun.

‘As you go farther from the sun, the magnetic field strength drops faster than the pressure of the material does,’ said Craig DeForest, lead author of the paper and a solar physicist at the Southwest Research Institute in Boulder, Colorado.

‘Eventually, the material starts to act more like a gas, and less like a magnetically structured plasma.’

Before this study, scientists hypothesized that magnetic forces were instrumental to shaping the edge of the corona.  However, the effect has never previously been observed because the images are so challenging to process. Twenty million miles from the sun, the solar wind plasma is tenuous, and contains free-floating electrons which scatter sunlight.

This means they can be seen, but they are very faint and require careful processing.  The Earth protects itself from solar storms using an invisible shield known as the ‘magnetosphere’. But because Earth’s magnetic poles are continually moving, the magnetosphere is weakening.This means our planet is increasingly vulnerable to the potentially devastating effects of solar flares.

Now, Joseph Pelton, former dean of the International Space University, in Illkirch-Graffenstaden in France, has called for scientists to take action by creating a massive magnetic shield to protect Earth.

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