The peak of this distribution as a function of wavelength can be found by taking the derivative of P_{e}(λ) with respect to wavelength, setting the value equal to 0, and solving for the wavelength. The result is the **Wien Displacement Law**:

$${\lambda}_{\mathrm{max}imum}=\frac{2890\text{\hspace{0.17em}}(\mu m\text{\hspace{0.17em}}K)}{T}$$

For the sun with a photospheric temperature of about 5780 K, λ_{max} ~ 0.500 μm or 500 nm, which is the color green. However, for Earth with a mid-tropospheric temperature of about 260 K, the peak wavelength is closer to 11 μm, well into the infrared (see below).

Credit: W. Brune