In the mid-1960s, Arno Penzias and Robert Wilson detected leftover, cooled down radiation from early in the Universe's history by carefully scanning the sky with a device called the Holmdel Horn Antenna. Their discovery was of huge importance to cosmology and won them the Nobel prize.
This cosmic microwave background radiation was later mapped in greater detail by NASA's Cosmic Background Explorer (COBE) mission in the early 1990s and the Wilkinson Microwave Anisotropy Probe (WMAP), launched in 2001.
Image: Arno Penzias (left) and Robert Wilson in 1978 outside the Holmdel horn antenna (credit: Physics Today Collection/AIP/SPL)
Astronomers find traces of the early Universe.
Scientists map the early Universe.
The astronomers Arno Penzias and Robert Wilson discovered the cosmic microwave background (CMB) radiation by chance in the mid-1960s while using the Holmdel Horn Antenna in New Jersey to map the sky. The CMB was later mapped with satellites, including the WMAP probe.
Arno Penzias talks about detecting ancient cosmic radiation.
Arno Penzias describes observations (made with Robert Wilson) using the Holmdel Horn Antenna. These observations would later be identified as the cosmic microwave background radiation (CMB).
The accidental discovery of cosmic microwave background radiation in 1964 is a major development in modern physical cosmology. Although predicted by earlier theoretical work around 1950, it was first discovered accidentally by American radio astronomers Arno Penzias and Robert Woodrow Wilson as they experimented with the Holmdel Horn Antenna. The discovery was important evidence for a hot early Universe (big bang theory) and was evidence against the rival steady state theory. In 1978, Penzias and Wilson were awarded the Nobel Prize for Physics for their joint discovery.