The proportion of incident radiation that is reflected by a non-self-illuminating body. Albedo is measured in a scale from 0 to 1, 0 referring to a perfectly absorbing black object, and 1 referring to a perfectly reflecting white object. Spherical albedo assumes that the object is a perfect sphere, with a diffuse surface that reflects incoming parallel light in all directions. Bond albedo is the fraction of the total incident energy reflected in all directions and calculated over all wavelengths. Geometrical albedo is the ratio of the reflectance of the object to the reflectance that would be produced by a flat white surface of the same surface area at the same distance.