Scientists have recently gathered some of the strongest evidence to date to explain what makes the sun's outer atmosphere so much hotter than its surface. The new observations show temperatures in the atmosphere so hot that only one current theory explains them: something called nanoflares – a constant peppering of impulsive bursts of heating, none of which can be individually detected — provide the mysterious extra heat.
These 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, launched on April 23, 2013, gathering 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 unique capabilities of EUNIS enabled researchers to obtain these results. The spectrograph was able to clearly and unambiguously distinguish the observations representing the extremely hot material – emission lines showing light with a wavelength of 592.6 angstrom, where an angstrom is the size of an atom — from a very nearby light wavelength of 592.2 angstroms.
GCMD keywords can be found on the Internet with the following citation:
Olsen, L.M., G. Major, K. Shein, J. Scialdone, S. Ritz, T. Stevens, M. Morahan, A. Aleman, R. Vogel, S. Leicester, H. Weir, M. Meaux, S. Grebas, C.Solomon, M. Holland, T. Northcutt, R. A. Restrepo, R. Bilodeau, 2013. NASA/Global Change Master Directory (GCMD) Earth Science Keywords. Version 188.8.131.52.0