The Big Bang

In 1965, Bell-labs scientists Arno Penzias and Robert Wilson discovered the Cosmic Microwave Background, an electromagnetic echo of the origin of the universe. The Big Bang has now entered into popular culture, but most people have no idea really what it means for cosmology. This web page will explain the history behind the 1965 measurements, and provide resources and links so you can learn what it all means!

The Cosmic Microwave Background (CMB) is the cooled remnant of the first light that could ever travel freely throughout the Universe. This 'fossil' radiation, the furthest that any telescope can see, was released soon after the 'Big Bang'. Scientists consider it as an echo or 'shockwave' of the Big Bang. Over time, this primeval light has cooled and weakened considerably; nowadays we detect it in the microwave domain.

The CMB radiation was discovered by chance in 1965 when two radio astronomers in the United States, Penzias and Wilson, registered a signal in their radio telescope that could not be attributed to any precise source in the sky. It apparently came from everywhere with the same intensity, day or night, summer or winter. They concluded that the signal had to come from outside our Galaxy; from the origin of the Universe.

The following websites provide further insight into CMB and relevant NASA missions:

The Planck Mission launched on May 14, 2009, and measures the Cosmic Microwave Background over a broad range of far-infrared wavelengths. Explore resources for general audiences, informal education, and higher education that helps to explain CMB and the mission itself.
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Follow the Planck space observatory’s updates from the European Space Agency (ESA).
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Learn about the Wilkinson Microwave Anisotropy Probe (WMAP), a NASA Explorer mission that launched June 2001 to make fundamental measurement of cosmology.
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More information about Cosmic Light coming soon at