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
Albedo 0.39 light it receives that is reflected back into space. The album title refers to the average albedo value of the planet Earth as it was in 1976. From the explanation on the back of the LP cover : ""The reflecting power of a planet or other non-luminous body. A perfect reflector would have an Albedo of 100%. The Earth's Albedo is 39%, or 0.39"". As with "Heaven and Hell", it was performed at the Royal Albert Hall in 1977. The album reached #18 on the UK Album Charts. In 2011 the album was included along with "Heaven and Hell" and