Portal:Astronomy/Picture/14 August 2005

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The Wilkinson Microwave Anisotropy Probe is a satellite owned by NASA that measures leftover energy from the big bang. This photo is an image measuring anisotropies in the cosmic microwave background radiation, which could be considered the cooled remnants of the big bang. The CMB gives a snapshot of the universe when, according to standard cosmology, the temperature dropped enough to allow electrons and protons to form hydrogen atoms, thus making the universe transparent to radiation, and leaving only loose electron microwaves as background radiation. Before this point, highly energetic matter and radiation was simply absorbed and expelled in a process known as Compton scattering.