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
Surface brightness object is large. What counts as small or large depends on the specific viewing conditions and follows from Ricco's law. In general, in order to adequately assess an object's visibility one needs to know both parameters. Surface brightnesses are usually quoted in magnitudes per square arcsecond. Because the magnitude is logarithmic, calculating surface brightness cannot be done by simple division of magnitude by area. Instead, for a source with a total or integrated magnitude "m" extending over a visual area of "A" square arcseconds, the surface brightness "S" is given by formula_1 For astronomical objects, surface brightness is analogous to