Figure 25-7: COBE and the Spectrum of the Cosmic Microwave Background (a) The Cosmic Background Explorer (COBE), launched in 1989, measured the spectrum and angular distribution of the cosmic microwave background over a wavelength range from 1 μm to 1 cm. (b) A blackbody curve gives an excellent match to the COBE data.

(a: Courtesy of J. Mather/NASA; b: Courtesy of E. Cheng/NASA COBE Science Team)