Albedo formula_5 (also called blue-sky albedo) can then be given as: Directional-hemispherical reflectance is sometimes referred to as black-sky albedo and bi-hemispherical reflectance as white-sky albedo. These terms are important because they allow the albedo to be calculated for any given illumination conditions from a knowledge of the intrinsic properties of the surface. The albedos of planets, satellites and minor planets such as asteroids can be used to infer much about their properties. The study of albedos, their dependence on wavelength, lighting angle ("phase angle"), and variation in time comprises a major part of the astronomical field of photometry. For small
Albedo 0.39 track, "Albedo 0.39" is an atmospheric track building on waxing and waning synthesizer chords and arpeggios, while a voice, reputedly the album's engineer Keith Spencer-Allen, narrates various physical properties of the Earth, such as its mass, length of the year in various measurements, and, finally, its albedo. Mike DeGagne of Allmusic described the tracks as "mesmerizing trips of assorted rhythms that include elements of jazz and mild rock", that along with "Albedo 0.39", "the two parts of "Nucleogenesis" are among the strongest cuts that keep his cosmic theme from deviating, while the livelier "Pulstar" involves some impressive instrumental range and