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The visible surface of the Sun, or the photosphere, is around 6,000°C. But a few thousand kilometers above it – a small distance when we consider the size of the Sun – the solar atmosphere, also called the corona, is hundreds of times hotter, reaching a million degrees celsius or higher. This spike in temperature, despite the increased distance from the Sun’s main energy source, has been observed in most stars, and represents a fundamental puzzle that astrophysicists have mulled over for decades. In 1942, the Swedish scientist Hannes Alfvén proposed an explanation. He theorized that magnetized waves of plasma...

...why is its outer atmosphere hotter than its fiery surface? University of Michigan researchers believe they have the answer, and hope to prove it with help from NASA's Parker Solar Probe. In roughly two years, the probe will be the first manmade craft to enter the zone surrounding the sun where heating looks fundamentally different than what has previously been seen in space. This will allow them to test their theory that the heating is due to small magnetic waves travelling back and forth within the zone... Such high temperatures cause the solar atmosphere to swell to many times the...

A new 3D model linking magnetic fields to the transfer of energy in space might help solve a physics mystery first observed in the solar wind 15 years ago. Scientists at The University of Alabama in Huntsville and Ruhr University in Bochum, Germany, developed the simulation while studying turbulence and energy transfer in the plasma carried away from the sun in the solar wind... What Wind and the other spacecraft saw was particles in relatively small-scale solar wind eddies getting "hotter" than theories predicted they should get. A theory published in 1941 by mathematician Andrey Kolmogorov established a generally accepted...