Tag: Corona

A corona is a type of plasma “atmosphere” of the Sun or other celestial body, extending millions of kilometers into space, most easily seen during a total solar eclipse, but also observable in a coronagraph. The Latin root of the word corona means crown.
The high temperature of the corona gives it unusual spectral features, which led some to suggest, in the 19th century, that it contained a previously unknown element, “coronium”. These spectral features have since been traced to highly ionized iron (Fe-XIV) which indicates a plasma temperature in excess of 10 kelvin. The fact that the Sun has a million degree corona was first discovered by Gotrian in 1939 and Bengt Edlén in 1941 by identifying the coronal lines (observed since 1869) as transitions from low lying metastable levels of the ground configuration of highly ionized metals (the green FeXIV line at 5303 Å, but also the red line FeX at 6374 Å).
Light from the corona comes from three primary sources, which are called by…