We compare Planck’s distribution for spectral radiation with Callendar’s. We cover the two regimes of wavelengths and frequencies. In each of the four cases we evaluate the dependence of the spectral radiance on the temperature for the maximum, the standard deviation and the distance between the two inflection points. The astrophysical comparison of Planck’s and Callendar’s distributions covers the temperature of the sun, the temperature of the cosmic microwave background, the (B-V) color and the bolometric correction.
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