Albedo objects in the outer Solar System and asteroid belt have low albedos down to about 0.05. A typical comet nucleus has an albedo of 0.04. Such a dark surface is thought to be indicative of a primitive and heavily space weathered surface containing some organic compounds. The overall albedo of the Moon is measured to be around 0.136, but it is strongly directional and non-Lambertian, displaying also a strong opposition effect. Although such reflectance properties are different from those of any terrestrial terrains, they are typical of the regolith surfaces of airless Solar System bodies. Two common albedos that are
Bond albedo phase angles from the Earth, the only reliable data for measuring their Bond albedo comes from spacecraft. The Bond albedo ("A") is related to the geometric albedo ("p") by the expression where "q" is termed the "phase integral" and is given in terms of the directional scattered flux "I"("α") into phase angle "α" (averaged over all wavelengths and azimuthal angles) as The phase angle "α" is the angle between the source of the radiation (usually the Sun) and the observing direction, and varies from zero for light scattered back towards the source, to 180° for observations looking towards the source.