Any object with temperature T > 0 emits EM waves ( radiation )
at all wavelengths.
If the object is a perfect absorber, it will not
reflect any light. Call this a blackbody.
- A perfect absorber re-emits all light incident
- The emitted light has a special spectrum
called a blackbody spectrum.
Spectrum is the intensity of the line as the function of
- Blackbody spectrum is continous and
only depends on the surface temperature of the object.
The Sun radiation is almost blackbody