Echoes of the early Universe. False-colour microwave map of the whole sky, showing variations in the cosmic microwave background. The mean temperature of the background radiation (2.73 degrees Kelvin) is shown as deep blue; pink and red areas are warmer, while blue areas are cooler - red is +0.27 milliKelvins (mK), pale blue is -0.27mK. Computer analysis of the image shows that the pattern of fluctuations in the background is consistent with the inflationary Big Bang theory of the creation of the Universe, and the existence of invisible dark matter. Data obtained by the Differential Microwave Radiometer (DMR) on the Cosmic Background Explorer (COBE) satellite over two years.