Chronology of Cosmic Microwave Background Astronomy
| 1934 | Richard Tolman shows that blackbody radiation in an expanding universe cools but remains thermal. |
| 1941 | Andrew McKellar uses the excitation of CN doublet lines to measure that the "effective temperature of space'' is about 2.3 K. |
| 1948 | George Gamow, Ralph Alpher, and Robert Herman predict that a Big Bang universe will have a blackbody cosmic microwave background with temperature about 5 K. |
| 1955 | Tigran Shmaonov finds excess microwave emission with a temperature of roughly 3 K. |
| 1964 | A.G. Doroshkevich and Igor Novikov write an unnoticed paper suggesting microwave searches for the blackbody radiation predicted by Gamow, Alpher, and Herman. |
| 1965 | Arno Penzias, Robert Wilson, Bernie Burke, Robert Dicke, and James Peebles discover the cosmic microwave background radiation. |
| 1966 | Rainer Sachs and Arthur Wolfe theoretically predict microwave background fluctuation amplitudes created by gravitational potential variations between observers and the last scattering surface. |
| 1968 | Martin Rees and Dennis Sciama theoretically predict microwave background fluctuation amplitudes created by photons traversing time-dependent potential wells. |
| 1969 | R.A. Sunyaev and Yakov Zel'dovich study the inverse Compton scattering of microwave background photons by hot electrons. |
| 1990 | The COBE satellite shows that the microwave background has a nearly perfect blackbody spectrum and thereby strongly constrains the density of the intergalactic medium. |
| 1992 | The COBE satellite discovers anisotropy in the cosmic microwave background. |