Halo (religious iconography) obsolete "nimbated", like the commoner "nimbate", means "furnished with a nimbus". It is sometimes preferred by art-historians, as sounding more technical than halo. "Aureole", from the Latin for "golden", has been used in English as a term for a gold crown, especially that traditionally considered the reward of martyrs, since the Middle Ages (OED 1220). But the first use recorded as a term for a halo is in 1848, very shortly after which matters were greatly complicated by the publication in 1851 of the English translation of Adolphe Napoléon Didron's important "Christian Iconography: Or, The History of Christian Art in
Aureole effect plane. Although the focused (light) ray cones are actually more or less parallel to each other, the rays from the aureole effect appear to be radiating from the shadow of the viewer’s head due to perspective effects. The viewer's line of sight is parallel and lies within the cones, so from the viewer's perspective the rays seem to be radiating from the antisolar point, within the viewer's shadow. As in similar antisolar optical effects (such as a glory or Heiligenschein), each observer will see an aureole effect radiating only from their own head’s shadow. Similarly, if a photographer holds their