Mystery (Partially) Solved? 'Heat Bombs' Warm Sun's Outer Atmosphere
New observations from a NASA spacecraft could help solve a persistent mystery — why the sun's atmosphere is so much hotter than its surface.
While the sun's visible surface is about 10,000 degrees Fahrenheit (5,538 degrees Celsius), its upper atmosphere, known as the corona, has temperatures in the millions of degrees.
NASA's Interface Region Imaging Spectrograph (IRIS) spacecraft looks at the transition region between the sun's surface and the corona. The satellite recently saw evidence of "heat bombs," which occur when magnetic fields cross in the corona and realign, much like the process that causes solar flares.
"Because IRIS can resolve the transition region 10 times better than previous instruments, we were able to see hot material rushing up and down magnetic fields in the low corona," Paola Testa, an astrophysicist at the Harvard-Smithsonian Center for Astrophysics who led the research, said in a NASA statement. "This is compatible with models from the University of Oslo, in which magnetic reconnection sets off heat bombs in the corona."