Geometric albedo node of their orbit, and hence lie on the ecliptic. In practice, measurements at small nonzero phase angles are used to derive the parameters which characterize the directional reflectance properties for the body (Hapke parameters). The reflectance function described by these can then be extrapolated to zero phase angle to obtain an estimate of the geometric albedo. For very bright, solid, airless objects such as Saturn's moons Enceladus and Tethys, whose total reflectance (Bond albedo) is close to one, a strong opposition effect combines with the high Bond albedo to give them a geometric albedo above unity (1.4 in the
Single-scattering albedo other methods of computational electromagnetics. The albedo of particles of shapes which are easily parameterized in non-standard co-ordinate systems may be determined through solutions of Maxwell's equation analogues in such coordinate systems. Scattering albedo equations have yet to be determined in elliptical, torroidal, conical and many others. Derivation and solutions to such equations is a field of ongoing research. Single-scattering albedo Single-scattering albedo is the ratio of scattering efficiency to total extinction efficiency (which is also termed "attenuance", a sum of scattering and absorption). Most often it is defined for small-particle scattering of electromagnetic waves. Single-scattering albedo is unitless, and