Wien's Law tells us that objects of different temperature emit spectra that peak at different wavelengths.

• Hotter objects emit most of their radiation at shorter wavelengths; hence they will appear to be bluer .

• Cooler objects emit most of their radiation at longer wavelengths; hence they will appear to be redder.

Furthermore, at any wavelength, a hotter object radiates more (is more luminous) than a cooler one.