The CMB has been observed by many researchers now and with many spacecraft missions. One of the most famous space-faring missions to do so was NASA’s Cosmic Background Explorer (COBE) satellite, which mapped the sky in the 1990s.
Several other missions have followed in COBE’s footsteps, such as the BOOMERanG experiment (Balloon Observations of Millimetric Extragalactic Radiation and Geophysics), NASA’s Wilkinson Microwave Anisotropy Probe (WMAP) and the European Space Agency’s Planck satellite.
Planck’s observations, first released in 2013, mapped the CMB in unprecedented detail and revealed that the universe was older than previously thought: 13.82 billion years old, rather than 13.7 billion years old. The research observatory’s mission is ongoing and new maps of the CMB are released periodically.
The maps give rise to new mysteries, however, such as why the Southern Hemisphere appears slightly redder (warmer) than the Northern Hemisphere. The Big Bang Theory says that the CMB would be mostly the same, no matter where you look.
Examining the CMB also gives astronomers clues as to the composition of the universe. Researchers think most of the cosmos is made up of matter and energy that cannot be “sensed” with our conventional instruments, leading to the names “dark matter” and “dark energy.” It is thought that only 5% of the universe is made up of matter such as planets, stars and galaxies.
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