[0, pi]. See Particulars below
               for a detailed discussion of the definition.

               [1,1] = size(solar); double = class(solar)

      emissn   is the emission angle at `spoint', as seen from `obsrvr'
               at time `et'. This is the angle between the surface
               normal vector at `spoint' and the spoint-observer
               vector. Units are radians. The range of `emissn' is [0,
               pi]. See Particulars below for a detailed discussion of
               