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The Bond albedo is the fraction of total incident radiant power that a body reflects, summed over outgoing directions and over the incident spectrum. The absorbed fraction is $1-A_B$. It is a global energy-budget quantity, so it appears directly in the planetary equilibrium temperature and must lie between zero and one for a passive reflecting body.

A bright appearance from one direction does not determine Bond albedo. Geometric albedo measures full-phase brightness, and the planetary phase integral supplies the angular weighting needed to connect that brightness to reflected power at a given wavelength. The spectral weighting also depends on the illuminating star: the same reflecting material need not absorb the same fraction of light from hot and cool stars.

The geometric albedo $A_g$ compares the planet's reflected brightness at full phase with that of a perfectly reflecting Lambertian surface in the form of a flat disc of the same projected area, illuminated by the same incident flux. The Bond albedo $A_B$ is the fraction of total incident stellar power reflected in all directions and over all wavelengths. They need not be equal: the planetary phase integral and the incident spectral weighting connect them.

For a blackbody star, the incident flux at orbital distance $a$ isAssume negligible intrinsic luminosity, thermal emissivity one, and efficient day-night heat redistribution giving uniform emission over the whole planet. The absorbed and emitted powers areUsing the Stefan–Boltzmann law gives the planetary equilibrium temperatureFor a representative emitting area encoded by a stellar flux redistribution factor $f$, the equivalent expression iswith $f=1/4$ for global uniform emission and $1/2$ for uniform dayside-only emission. The Bond albedo, rather than the geometric albedo, belongs in the energy budget. Internal heat, wavelength-dependent emissivity and imperfect redistribution require corresponding modifications.