Scientists might have zeroed in on the phenomenon that heats the sun's outer atmosphere, or corona, to mind-bogglingly hot temperatures.
NASA's Interface Region Imaging Spectrograph (IRIS) spacecrafthas captured the first clear images of nanojets, which are bright thin lights that move perpendicular to magnetic structures in the solar atmosphere. These jets, in turn, show the existence of nanoflares, which are believed to drive coronal heating on the sun, which can reach over a million degrees Fahrenheit.
Nanoflares are small, but move rapidly and are difficult to spot on the bright sun. Researchers saw the bright jets on April 3, 2014 during a "coronal rain event." This occurred when cooled plasma (superheated gas) fell from the corona to the much cooler surface of the sun.
"Nanojets are considered a 'smoking gun,' key evidence of the presence of nanoflares," NASA said in a statement. "Each nanojet is believed to be initiated by a process known as magnetic reconnection, where twisted magnetic fields explosively realign. One reconnection can set off another reconnection, creating an avalanche of nanojets in the corona of the sun, a process that could create the energy that is heating the corona."
More studies are planned to learn how often nanojets and nanoflares occur, and how much energy they dump into the solar corona.
Two missions are peering at the sun up close, including NASA's Parker Solar Probe and the European Space Agency's Solar Orbiter. The hope is that by imaging the poles and dipping close to the sun, as these spacecraft will allow researchers to do, we will learn more about the processes that heat the solar corona.
A study based on the research was published in Nature Astronomy (opens in new tab) on Sept. 21
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