Used with
permission of Maiken Naylor, University at Buffalo, Buffalo, NY, USA,
http://ublib.buffalo.edu/libraries/units/sel/exhibits/stamps
Dark spectral lines on the solar emission continuum are caused by absorption of radiation in the outer, cooler layers of the solar atmosphere. Although observed before, they were first mapped by Joseph von Fraunhofer (1787-1826), German physicist and inventor of the transmission grating. This illustrative stamp shows the Fraunhofer lines in the solar spectrum, which approximates that of a black body with 5800 degree K effective temperature peaking in the yellow, as we see each sunny day.