The topic of solar wind has been discussed since it’s discovery in 1959, but, there’s still a lot that we don’t know about it. One of solar winds’ mysteries surrounds the fact that when it reaches the Earth, satellite measurements are recording temperatures that are hotter than the laws of physics would predict. Physicists from the University of Wisconsin - Madison may now know the reason why this is with their study that was published April 14 in the Proceedings of the National Academy of Sciences. What is Solar Wind?  To understand the study’s findings, we must first cover what we know about solar wind up to this point. Solar plasma is a molten mix of negatively charged electrons and positively charged ions that are influenced by magnetic fields that extend into space, generated underneath the solar surface. As hot plasma escapes from the sun’s outermost atmosphere, it flows through space as solar wind. The idea is that during this journey through space, the solar wind will cool down before it enters the Earth.  Solar Winds and Plasma Fusion Around the same time scientists discovered solar wind, plasma fusion researchers were thinking of ways to confine plasma -- developing “mirror machines” or plasma-filled, magnetic field lines shaped like open neck bottles. As charged particles in the plasma travel along the field lines and reach the bottleneck, the magnetic field lines are pinched. This pinch acts as a mirror, reflecting particles back into the machine. But, not all particles make it through the bottleneck.  Stas Boldyrev, professor of physics at UW-Madison and lead author of the study, says this mirror machine theory, "is very similar to what's happening with solar wind that expands away from the sun." The Study’s Findings In mirror machine studies, it’s been found that very hot electrons escaping the bottle were able to distribute their heat energy slowly to the trapped electrons. In the study, Boldyrev says, “it turns out that our results agree very well with measurements of the temperature profile of the solar wind and they may explain why the electron temperature declines with the distance so slowly.”  In the solar wind, hot electrons are released from the sun over large distances, where they lose their energy very slowly and distribute it to the trapped population. This slow distribution of energy causes the winds to not cool down as rapidly as expected.  Learn More With Apex Magnets Their findings suggest ways to study solar wind phenomena in research labs and learn about solar wind properties in other solar systems so more news can be expected in the future. On the topic of solar wind, did you know magnets protect astronauts from solar wind? It’s true! Check out the blog post explaining how here.