Albedo distribution of solar radiation reaching the Earth's surface. These factors vary with atmospheric composition, geographic location and time (see position of the Sun). While bi-hemispherical reflectance is calculated for a single angle of incidence (i.e., for a given position of the Sun), albedo is the directional integration of reflectance over all solar angles in a given period. The temporal resolution may range from seconds (as obtained from flux measurements) to daily, monthly, or annual averages. Unless given for a specific wavelength (spectral albedo), albedo refers to the entire spectrum of solar radiation. Due to measurement constraints, it is often given
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