All objects emit heat. The hotter an object, the faster its molecules move and the shorter...

All objects emit heat. The hotter an object, the faster its molecules move and the shorter the wavelength of radiation it emits. This relationship between the heat of a body and wavelength is expressed in Wien’s law, which states that the maximum wavelength (in micrometers) of electromagnetic radiation can be determined by dividing 2,897 by the absolute temperature (T). Absolute temperatue T is expressed in kelvins (K). The Kelvin temperature scale begins at absolute 0 (where all particle motion stops), with the freezing point of water (0°C) equivalent to 273 K on this scale (30°C = 303 K).

For example, for the sun, T = 6,000 K. Substituting the temperature of the sun into the above equation illustrates that incoming solar radiation should have a wavelength of approximately 0.5 micrometer, which lies within the range of visible light.

Use Wien’s law to determine the dominant wavelengths emitted from (a) Earth and (b) Venus, and identify the corresponding type of radiation.