Albedo formula_5 (also called blue-sky albedo) can then be given as: Directional-hemispherical reflectance is sometimes referred to as black-sky albedo and bi-hemispherical reflectance as white-sky albedo. These terms are important because they allow the albedo to be calculated for any given illumination conditions from a knowledge of the intrinsic properties of the surface. The albedos of planets, satellites and minor planets such as asteroids can be used to infer much about their properties. The study of albedos, their dependence on wavelength, lighting angle ("phase angle"), and variation in time comprises a major part of the astronomical field of photometry. For small
Albedo (alchemy) Albedo (alchemy) In alchemy, albedo is one of the four major stages of the magnum opus; along with nigredo, citrinitas and rubedo. It is a Latinicized term meaning "whiteness". Following the chaos or "massa confusa" of the nigredo stage, the alchemist undertakes a purification in albedo, which is literally referred to as "ablutio" – the washing away of impurities. In this process, the subject is divided into two opposing principles to be later coagulated to form a unity of opposites or "coincidentia oppositorum" during rubedo. Titus Burckhardt interprets the albedo as the end of the lesser work, corresponding to a