A detailed view of the Cosmic Microwave Background from WMAP, compared to the original view from the COBE satellite.
Click on image for full size
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.

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Capturing the Afterglow of the Big Bang

According to the Big Bang theory, the universe began about 12-14 billion years ago. Right after the Big Bang, the universe was really hot! But, as the universe has expanded, the particles within the universe...more

Capturing the Afterglow of the Big Bang (Updated!)

Some of the best news of the week is that the Microwave Anisotropy Probe (MAP) was launched successfully last Saturday! Liftoff on its Delta II rocket occurred on time at 15:46:46 EDT, June 30, 2001. So...more

The Oldest Light in the Universe

NASA scientists have taken a "snapshot" picture of the oldest light in the universe. The image shows the remains of light emitted during the big bang, which is now microwave energy. The light...more

Gamma Ray Bursts - The Most Powerful Objects in the Universe?

In the 1960's, the United States launched a series of satellites to look for very high energy photons, called Gamma Rays, that are produced whenever a nuclear bomb explodes. These satellites soon detected...more


The introduction of telescopes to the study of astronomy opened up the universe, but it took some time for astronomers to realize how vast the universe could be. Telescopes revealed that our night sky...more

Neutron Stars

Neutron Stars are the end point of a massive star's life. When a really massive star runs out of nuclear fuel in its core the core begins to collapse under gravity. When the core collapses the entire star...more

Spiral Galaxies

Spiral galaxies may remind you of pinwheels turning slowly as though in some intergalactic breeze. They are rotating disks of gas, dust and stars. Through a telescope or binoculars, the bright nucleus...more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part is sponsored in part through grants from federal agencies (NASA and NOAA), and partnerships with affiliated organizations, including the American Geophysical Union, the Howard Hughes Medical Institute, the Earth System Information Partnership, the American Meteorological Society, the National Center for Science Education, and TERC. The American Geophysical Union and the American Geosciences Institute are Windows to the Universe Founding Partners. NESTA welcomes new Institutional Affiliates in support of our ongoing programs, as well as collaborations on new projects. Contact NESTA for more information. NASA ESIP NCSE HHMI AGU AGI AMS NOAA