Wilkinson Microwave Anisotropy Probe, WMAP: This is a map of the universe depicting radiation produced by the primordial explosion, Big Bang, 13.7 billion years ago. It is a measurement of temperature fluctuations in the microwave spectrum (20 to 100 gigahertz) showing the cosmos when it was about 379,000 years old. The temperature at this time is 2.725 degrees Kelvin. The map’s color variations show regions slightly hotter, 0.0004 Kelvin, than the surrounding areas, producing essential variations in the cosmic structure – future galaxies. NASA photo and caption.