Definitions

1. 1.halo (circular band of coloured light, visible around the sun or moon, etc., caused by reflection and refraction of light by ice crystals in the atmosphere)
2. 2.halo (cloud of gas and other matter surrounding and captured by the gravitational field of a large diffuse astronomical object, such as a galaxy or cluster of galaxies)
3. 3.halo (luminous border in a photograph around shiny or reflective objects)
4. 4.halo (metaphorical aura of glory, veneration, or sentiment which surrounds an idealized entity)