Luminosities are typically referred to as the brightness or radiance of something. Synonyms for luminosities include the terms brilliance, radiance, glow, shine, gleam, twinkle, and luster. Commonly used in discussions pertaining to stars and celestial objects, luminosities help to determine the size and mass of a star through its brightness. The term luminosity is also often applied to objects such as light bulbs, lamps, and headlights. The word can also be used to describe the brightness of something that is not necessarily emitting light, such as the glow of a person's eyes or the sheen of polished metal.