Wilkinson Microwave Anisotropy Probe (WMAP)

United States satellite

Also known as: WMAP

Written by

Dave Dooling

Fact-checked by

Britannica Editors

History

Wilkinson Microwave Anisotropy Probe (WMAP), a U.S. satellite launched in 2001 that mapped irregularities in the cosmic microwave background (CMB). The CMB was discovered in 1964 when German American physicist Arno Penzias and American astronomer Robert Wilson determined that noise in a microwave receiver was in fact residual thermal radiation from the big bang. The thermal radiation started as light and has been redshifted by the expansion of the universe to longer wavelengths where its...