The chromosphere and the corona only be seen from Earth during an eclipse because of where the light of the corona comes from.
The corona of the Sun is most easily seen during a total solar eclipse, but can also be seen in a coronagraph.
The chromosphere is a thin layer of the Sun's atmosphere just above the photosphere. It is so thin, it can only be seen during an eclipse when the rest of the Sun is blocked and only that thin layer is visible.
