What is the wavelength at which the human body emits the most radiation?
Using Wien's Law, one can calculate the peak in the emission spectra from an ideal blackbody.
Wien's displacement constant
Human body temperature is about
That puts the peak radiation in the infrared range. Human vision can see red light wavelengths as long as about 7,000 Angstroms. The infrared wavelengths are generally defined as being between 7,000 and 1,000,000 Angstroms.