A measure of the reflectivity of a surface, particularly that of a Solar System object such as a planet, a satellite, or an asteroid; also called physical albedo. The geometrical albedo is the ratio between the light or other radiation reflected from an object, as viewed from the direction of the Sun (i.e. at zero phase angle), and that which would be reflected by a hypothetical white, perfectly diffusely reflecting sphere (i.e. with an albedo of 1.0); this hypothetical sphere is assumed to have the same apparent size and be at the same distance as the real object. The wavelength or range of wavelengths at which the geometrical albedo applies must be defined. The bolometric geometrical albedo refers to reflectivity over all wavelengths.
Subjects: Astronomy and Astrophysics.