Electromagnetic radiation remaining from the early development of the universe. It fills the known universe and can be detected from every direction in space. Its existence is physical corroboration of the Big Bang theory for the formation of the universe around 13.7 billion years ago. It has an overall background temperature of −270.4°C/−454.8°F (around 3°C above absolute zero).
CMBR was first detected in 1965 by US physicists Arno Penzias and Robert Wilson, who in 1978 shared the Nobel Prize for Physics for their discovery.
In 1992 the US Cosmic Background Explorer (COBE) satellite detected very small changes in the strength of CMBR that are believed to mark the first stage in the formation of galaxies. George Smoot and John C Mather won the Nobel Prize for Physics in 2006 for determining very small changes of temperature in the CMBR in different directions, known as anisotropy, using data collected by COBE.
In 2001, NASA launched the Wilkinson Microwave Anisotropy Probe (WMAP), which has measured and mapped the temperature of the CMBR over the entire sky. Data from WMAP was published in 2012 and provided further direct physical evidence to support and update the standard model of cosmology.
In 2009, the European Space Agency launched the Planck spacecraft to map the CMBR over the whole sky with higher sensitivity and angular resolution than any of the previous missions.
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