Science Alert:  We know that particles making up the plasma of the Sun’s heliosphere cool as they spread out. The problem is that they seem to take their sweet time doing so, dropping in temperature far slower than models predict.
 “People have been studying the solar wind since its discovery in 1959, but there are many important properties of this plasma which are still not well understood,” says physicist Stas Boldyrev from the University of Wisconsin–Madison.
 “Initially, researchers thought the solar wind has to cool down very rapidly as it expands from the Sun, but satellite measurements show that as it reaches the Earth, its temperature is 10 times larger than expected.”
 The research team used laboratory equipment to study moving plasma, and now think the answer to the problem lies in a trapped sea of electrons that just can’t seem to escape the Sun’s grip.
The expansion process itself has long been assumed to be subject to adiabatic laws, a term that simply means heat energy isn’t added or removed from a system. This keeps the numbers nice and simple, but assumes there aren’t places where energy slips in or out of the flow of particles.