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A detailed view of the Cosmic Microwave Background from WMAP, compared to the original view from the COBE satellite.
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NASA/WMAP Science Team

The Cosmic Microwave Background Radiation

In the 1960's another startling discovery was made quite by accident. A pair of scientists at Bell Laboratories detected some annoying background noise using a special low noise antenna. The strange thing about the noise was that it was coming from every direction and did not seem to vary in intensity at all. They had discovered the Cosmic Microwave Background Radiation.

This radiation permeates the entire Universe and is no stronger or weaker in any direction. It has a perfect blackbody spectrum, meaning it behaves like radiation from an object that absorbs and emits all radiation that falls upon it. Its temperature is 2.7 degrees Kelvin (-454.81 degrees Farenheit). It has only minute fluctuations that were only detectable by the very sensitive space craft the Cosmic Background Explorer, COBE. This radiation is believed to be the remanant of the Universe's brilliant beginning, known as the Big Bang.

More recently, the Wilkinson Microwave Anisotropy Probe (WMAP) team has made a more detailed full-sky map of this oldest light in the universe. The WMAP image brings the COBE picture into sharp focus, and provides firm answers to age-old questions. WMAP resolves slight temperature fluctuations, which vary by only a few millionths of a degree. These new data support and strengthen the Big Bang and Inflation Theories.

Last modified April 29, 2005 by Travis Metcalfe.

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The Summer 2010 issue of The Earth Scientist, available in our online store, includes articles on rivers and snow, classroom planetariums, satellites and oceanography, hands-on astronomy, and global warming.

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