PlanetPhysics/Planck's Radiation Law

The spectral radiance of a black body per unit solid angle is given by: $$ I(\lambda,T) = \frac{ 2 h c^2}{\lambda^5} \, \frac{1}{e^{hc/ \lambda kT} - 1} $$ It can also be given as a function of frequency: $$ I(\nu,T) = \frac{2 h \nu^3}{c^2} \, \frac{1}{e^{hc/ \lambda kT} - 1} $$