The cosmic microwave background (CMB) holds an immense amount of information about the universe’s properties. The key is to map this radiation in such a way to capture the smallest detail. Scientists have come a long way since first detecting the CMB in the mid-1960s. At the end of 2012, researchers with the Wilkinson Microwave Anisotropy Probe released the mission’s final data, which shows the CMB’s variations smaller than 0.3° across and temperature differences of a few parts in 100,000.
So, how have CMB probes changed the appearance of sky maps changed since the first observation in 1965?
This simulated image shows what the CMB would have looked like if scientists had the ability to map the entire sky in 1965. The detector would have measured the same temperature in all directions; the white component along the horizontal center is emission from the Milky Way’s disk.
The COsmic Background Explorer (COBE) was launched in 1989 to map the CMB. COBE could image with a resolution of roughly 7° and thus showed that the temperature of the CMB was nearly a uniform 2.725 kelvins, with a small variation of a few parts per 100,000 — presented as the different colors in this map.
NASA launched the Wilkinson Microwave Anisotropy Probe in 2001 to further resolve the CMB variations. This spacecraft mapped detail some one-twentieth finer than COBE.
In 2009, the European Space Agency launched the Planck mission, which is currently mapping detail in the CMB to resolutions of 5–10 arcminutes. Scientists expect the Planck team to release its CMB data in the spring of this year. This image shows a simulated CMB map, as Planck should see it.
