Albedo is a term used to refer to the amount of light that an object reflects. The term is typically used in science, especially in astronomy, as well as in photography and computer generated imagery (CGI), where understanding of reflective surfaces often plays an important role in making materials look realistic. There is no specific unit used in measuring an object’s albedo, and the scale used is typically either between 0 and 1, where 0 is a non-reflective “black body” surface and 1 represents total reflection of light or a “white body.” It is also measured as a percentage with a maximum limit of 100%.
Originally a Latin word, albedo means “whiteness” and is rarely used outside of scientific and specialized fields of artistic creation. In astronomy, it is often used in the study of distant objects, either within our own solar system or far beyond our immediate neighbors, such as planetary bodies orbiting distant stars. For understanding such distant objects, knowing how light reacts to different types of materials can make it easier to understand what is seen and measured about those objects.
For example, freshly fallen snow has an albedo rating of about 0.9, ice is 0.5, and expanses of sand are about 0.4. If an astronomer is able to accurately gauge a distant planet as having an albedo generally of about 0.4 then he or she can begin to narrow down the properties of that world. While it may not be immediately possible to determine if it is made up principally of deserts, there is at least some quantifiable evidence to support such a claim. This is, of course, made more difficult in that many planets do not consist of a single type of environment, and clouds and other atmospheric factors often affect the albedo of a planet. However, it can provide useful information.
Albedo is sometimes used in photography and CGI as well, though for somewhat different purposes. When photographing a surface, it can be helpful for a photographer to understand how light will be affected by the surface, so unsightly lens flares and other photographic anomalies can be avoided. For computer artists, it can be extremely important to understand the albedo of a type of material to better ensure the computer version of that material matches reality. Reflectivity of surfaces plays a large role in how people observe different objects and immediately recognize whether something is made from metal, wood, or plastic. Understanding how these different appearances require different textures and levels of reflectivity, makes for more realistic and accurate digital creations.
