Geometric albedo For Earth-bound observers this occurs when the body in question is at opposition and on the ecliptic. The visual geometric albedo refers to the geometric albedo quantity when accounting for only electromagnetic radiation in the visible spectrum. The surface materials (regoliths) of airless bodies (in fact, the majority of bodies in the Solar System) are strongly non-Lambertian and exhibit the opposition effect, which is a strong tendency to reflect light straight back to its source, rather than scattering light diffusely. The geometric albedo of these bodies can be difficult to determine because of this, as their reflectance is strongly peaked
Albedo feature has fallen somewhat into disuse. It is however still used for Earth-based observing of Mars by amateur astronomers. However, for some Solar System bodies (such as Pluto prior to the New Horizons mission), the best available images show only albedo features. These images were usually taken by the Hubble Space Telescope or by ground-based telescopes using adaptive optics. Cydonia Mensae on Mars is an example of an albedo feature. Albedo feature An albedo feature is a large area on the surface of a planet (or other solar system body) which shows a contrast in brightness or darkness (albedo) with adjacent