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.
A meteorological phenomenon: rings of colored light seen around the observer's shadow on clouds or fog. Often written 御光 in this sense.
A golden halo is painted behind the Buddha statue.
He looked as if he had a halo around him.
From the airplane, I saw a glory around my shadow cast on the clouds.
halo effect
Standard kanji spelling for the religious/figurative halo sense.
Especially used for the optical phenomenon (glory).
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.