noun
Only when written 後光
Refers to the radiant light depicted around holy figures in religious art, or figuratively to an aura of greatness around a person.
仏像の後ろに金色の後光が描かれている。
A golden halo is painted behind the Buddha statue.
彼はまるで後光が差しているように見え
noun
A meteorological phenomenon: rings of colored light seen around the observer's shadow on clouds or fog. Often written 御光 in this sense.
飛行機から雲に映る自分の影の周りに御光が見えた。
From the airplane, I saw a glory around my shadow cast on the clouds.
He looked as if he had a halo around him.
光輪 is a more general term for a ring of light, often used for halos in art or astronomy, while 後光 specifically implies a radiant aura behind a sacred figure.
後光 is composed of 後 (behind) and 光 (light), literally 'light from behind'. The reading ごこう is the on'yomi. The variant 御光 uses 御 as a phonetic equivalent for 後.