The tenuous outermost layer of the sun, called the corona, is invisible most of the time, but its magnetic fields have been mapped for the first time
Source:
https://www.newscientist.com/article/2251150-maps-of-the-suns-corona-could-help-us-predict-dangerous-solar-storms/?utm_campaign=RSS%7CNSNS&utm_source=NSNS&utm_medium=RSS&utm_content=home