Stellar corona

A corona (pl.: coronas or coronae) is the outermost layer of a star's atmosphere. It consists of plasma.

The Sun's corona lies above the chromosphere and extends millions of kilometres into outer space. It is most easily seen during a total solar eclipse, but it is also observable with a coronagraph. Spectroscopic measurements indicate strong ionization in the corona and a plasma temperature in excess of 1000000 kelvins, much hotter than the surface of the Sun, known as the photosphere.

Corona (Latin for 'crown') is, in turn, derived from Ancient Greek κορώνη (korṓnē) 'garland, wreath'.