noun
Astronomical term for the luminous ring or halo around a celestial body, especially the sun's corona visible during a total solar eclipse.
皆既日食のとき、太陽の光環がはっきりと見えた。
During the total solar eclipse, the sun's corona was clearly visible.
The loanword コロナ is more common in everyday contexts, while 光環 is a technical astronomical term.
Compound of 光 (light) and 環 (ring), referring to a ring of light. The alternate spelling 光冠 uses 冠 (crown) for a similar visual metaphor.