Southwest Research Institute | 2015 Oct 13
[c][attachment=0]encke-tail[1].jpg[/attachment][/c][hr][/hr]We can’t see the wind, but we can learn about it by observing things that are being blown about. And by studying changes in a comet’s bright tail of gas and ions, scientists are on the trail to solving two big mysteries about the solar wind, the supersonic outflow of electrically charged gas from the Sun’s million-degree upper atmosphere or corona.
A team of scientists led by the heliophysics group at Southwest Research Institute (SwRI) has used observations of Comet Encke’s tail using NASA’s Solar and Terrestrial Relations Observatory, or STEREO, revealed that the solar wind flows through the vacuum of interplanetary space much as the wind blows on Earth: not smoothly, but with gusting turbulence and swirling vortices.
That turbulence can help explain two of the wind’s most curious features: its variable nature and unexpectedly high temperatures. ...
Scientists know a lot about the properties and behavior of the solar wind but don’t agree about how it is accelerated, especially at its fastest speeds. Moreover, the solar wind can be highly variable, so that measurements just short times or distances apart can yield quite different results. It is also very, very hot – hotter than it should be at such great distances from the Sun’s corona. ...
Turbulence in the Solar Wind Measured with Comet Tail Test Particles - C. E. DeForest et al
- Astrophysical Journal 812(2):108 (2015 Oct 20) DOI: 10.1088/0004-637X/812/2/108