[en] The ultraspherical polynomial approximation which unifies all classical polynomial sequences in a unique form is used to calculate the albedo for isotropic scattering in a homogeneous spherical medium. This is the most general polynomial approach in the sense that it includes all classical polynomial methods to solve the transport equation such as P_N, T_N and U_N methods. For the first time an antisymmetric polynomial (ultraspherical polynomial P_N^(λ)) solution to the corresponding pseudo-slab problem is proposed. Very accurate and consistent albedo values are obtained for a variety of P_N^(λ) methods when compared to the literature. It is also shown that various P_N^(λ) approximations differ only in convergency characteristics; some converge monotonically, some in the mean. (orig.)