Timeline of cosmic microwave background astronomy

• 1934 - Richard Tolman shows that black-body 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 black-body 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 Dmitrievich Novikov write an unnoticed paper suggesting microwave searches for the black-body 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 (see Integrated Sachs Wolfe effect)
• 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 (see Sunyaev-Zeldovich effect)
• 1983 - Researchers from the Cambridge Radio Astronomy Group and the Owens Valley Radio Observatory first detect the Sunyaev-Zeldovich effect from clusters of galaxies
• 1990 - The Cosmic Background Explorer (COBE) satellite shows that the microwave background has a nearly perfect black-body spectrum and thereby strongly constrains the density of the intergalactic medium.
• 1992 - The COBE satellite discovers anisotropy in the cosmic microwave background.
• 1995 - The Cosmic Anisotropy Telescope performs the first high resolution observations of the cosmic microwave background.
• 1999 - The Boomerang experiment makes higher quality maps at intermediate resolution, and confirms that the Universe is "flat".
• 2003 - The Very Small Array produces yet higher quality maps at high resolution (covering small areas of the sky).
• 2003 - The WMAP satellite produces an even higher quality map at low and intermediate resolution of the whole sky (WMAP provides no high-resolution data, but improves on the intermediate resolution maps from Boomerang).
• 2004 - The Arcminute Cosmology Bolometer Array Receiver produces a higher quality map of the high resolution structure not mapped by WMAP.
• 2005 - The Arcminute Microkelvin Imager and the Sunyaev-Zel'dovic Array begin the first surveys for very high redshift clusters of galaxies using the Sunyaev-Zeldovich effect.

Future

• 2008 The CLOVER array will give an improved precision intermediate and high resolution map, and measure the B-mode polarization measurements
• 2009 The Planck (satellite) will give improved precision at all resolutions