text: Scientists observing this region once thought an odd green emission line from it was due to a new elementcalled "newtonium", but later discovered it was due to highly ionized ironÂ—Fe thirteen plus.
full_question: Scientists observing this region once thought an odd green emission line from it was due to a new elementcalled "newtonium", but later discovered it was due to highly ionized ironÂ—Fe thirteen plus. Phenomenaobserved in this region include polar plumes and helmet streamers. Alfven waves have been proposed as anenergy source for this region, and the magnetic reconnection theory makes use of spicules that extend into it.X-ray telescopes first discovered its namesake holes, which are the origins of solar wind. Huge amounts ofplasma can be released in its "mass ejections." Scientists are still confused as to why this region is so muchhotter than the Sun's surface. For 10 points, name this outermost layer of the Sun that's usually only visibleduring a solar eclipse. 
first_sentence: Scientists observing this region once thought an odd green emission line from it was due to a new elementcalled "newtonium", but later discovered it was due to highly ionized ironÂ—Fe thirteen plus.
raw_answer: corona [prompt on the Sun's atmosphere] 