Cosmic microwave background radiation (CMBR) was discovered accidentally by Arno Penzias and Robert Wilson on 20th May 1964. The two American radio astronomers received the 1978 Nobel Prize.
The CMBR is the oldest light in the universe and dates back to the epoch of recombination. It cannot be observed through an optical telescope and shows up only on sensitive radio telescopes.
The radiation is not associated with any star or galaxy and appears in the space between heavenly bodies.
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