"That's a bit of a puzzle," said Jeff Brosius, space scientist at NASA's Goddard Space Flight Center. "Things usually get cooler farther away from a hot source. When you're roasting a marshmallow you move it closer to the fire to cook it, not farther away."
Only recently Scientists have gathered some of the strongest evidence to explain what makes the sun's outer atmosphere so much hotter than its surface.
The new observations come from just six minutes worth of data from one of NASA's least expensive type of missions, a sounding rocket. The EUNIS mission, short for Extreme Ultraviolet Normal Incidence Spectrograph, was launched on April 23, 2013 to gather a new snapshot of data every 1.3 seconds to track the properties of material over a wide range of temperatures in the complex solar atmosphere
The sun's visible surface, called the photosphere, is some 6,000 Kelvins, while the corona regularly reaches temperatures which are 300 times as hot and EUNIS was able to pick up a wavelength of light corresponding to that 10 million degree material
The culprit is known as " Nanoflares " — a constant peppering of impulsive bursts of heating, none of which can be individually detected — provide the mysterious extra heat
"The fact that we were able to resolve this emission line so clearly from its neighbors is what makes spectroscopists like me stay awake at night with excitement," said Brosius. "This weak line observed over such a large fraction of an active region really gives us the strongest evidence yet for the presence of nanoflares""
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