Cosmic Microwave Background (image) California Institute of Technology Caption This is the cosmic microwave background as seen by the WMAP satellite. This radiation was emitted when the Universe was 380,000 years old and has an average temperature of 2.7 Kelvin. The red and blue spots are temperature fluctuations that differ from the average temperature by only 0.0002 degrees. The region of maximal variation is in the lower right quadrant. Credit NASA/WMAP Science Team Usage Restrictions None Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.