Comet Encke: A Solar Windsock

[Waspie_Dwarf]

Comet Encke: A Solar Windsock Observed by NASA’s STEREO

Much like the flapping of a windsock displays the quick changes in wind’s speed and direction, called turbulence, comet tails can be used as probes of the solar wind – the constant flowing stream of material that leaves the sun in all directions. According to new studies of a comet tail observed by NASA’s Solar and Terrestrial Relations Observatory, or STEREO, the vacuum of interplanetary space is filled with turbulence and swirling vortices similar to gusts of wind on Earth. Such turbulence can help explain two of the wind's most curious features: its variable nature and unexpectedly high temperatures. A paper on this work was published in “The Astrophysical Journal” on Oct. 13, 2015.

“The solar wind at Earth is about 70 times hotter than one might expect from the temperature of the solar corona and how much it expands as it crosses the void,” said Craig DeForest, a solar physicist at the Southwest Research Institute in Boulder, Colorado, and lead author on the study. “The source of this extra heat has been a mystery of solar wind physics for several decades.”

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