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The effective temperature (Teff, Teff, or black body temperature, TBB) of a body such as a star or planet is the calculated temperature of a black body that would produce the same total radiation as the star produces, i.e., the result of that kind of temperature determination. It can be considered an estimate of the body's surface temperature, imperfect for being determined at a distance and because a star's surface itself is ambiguous: the radiation reaches us from more than one depth into the star, and these layers have differing temperatures. The various temperature determination methods in use differ but do have some general agreement. Among other measures are the brightness temperature (based on a single wavelength or narrow passband) and the color temperature (based on a color index).