The albedo of an object's the extent to which it diffusely reflects light from the Sun. It's therefore a more specific form of the term reflectivity. Albedo's defined as the ratio of diffusely reflected to incident electromagnetic radiation. It's a unitless measure indicative of a surface's or body's diffuse reflectivity. The word's derived from Latin albedo "whiteness", in turn from albus "white", and was introduced into optics in by Johann Heinrich Lambert in his 1760 work Photometria. The ran… (More on Albedo)