What is the peak frequency of the Cosmic Microwave Background? Using Wien's Displacement (#1) and then converting the wavelength of frequency (#2), I get 282 GHz. #1. 0.0028977685 / 2.728 = 0.00106223185483871 Meters (1 millimeter) #2. 299792458 / 0.00106223185483871 = 282228834161.183 Hertz (282 GHz) This website seems to conclude that it's 160.4 GHz: http://hypertextbook.com/facts/2004/HeatherFriedberg.shtml Also, if something isn't a perfect black body, is there an easy way to get a more accurate result? Using the surface temperature of the Sun (5785) I get about 500 nanometers, which is green I believe. I imagined I should have gotten a frequency closer to yellow, around 570 nanometers.