Hevelian halo

[ huh-vey-lee-uh n ]
/ həˈveɪ li ən /

noun

a faint white halo with an angular radius of 90° that is occasionally seen around the sun or the moon, thought to be caused by the reflection and refraction of sunlight by ice crystals.

Origin of Hevelian halo

after J. Hevelius; see -ian