All bodies (objects) emit electromagnetic radiationEnergy travelling as waves in the form of changing electrical and magnetic fields., no matter what their temperature is. The type of radiation emitted depends on the temperature of the body.
Hot bodies emit a continuous range of electromagnetic radiation at different energy values - this means that the radiation that is emitted is spread out over a range of different frequencies and wavelengths.
As a body gets hotter, it emits more high frequency electromagnetic radiation than low frequency. The higher the frequency, the shorter the wavelength. This means that the intensityThe power transferred per unit area. of the radiation emitted is greater for a hotter body.
As the surface temperature of a hot body such as a star increases:
the intensity of the radiation it emits increases
the wavelength that corresponds to the peak intensity gets shorter
Poor absorbers and emitters
White and shiny silvery surfaces are the worst absorbers, as they reflect all visible light wavelengths. Poor absorbers are also poor emitters, and do not emit radiation as quickly as darker colours. Radiators in homes are usually painted white so that the infrared radiation is emitted gradually.
Jonny Nelson introduces an animated explanation of black body radiation