JOHN C. MATHER is a senior astrophysicist in the Observational Cosmology Laboratory at NASA’s Goddard Space Flight Center (GSFC). His research centers on infrared astronomy and cosmology. As a National Research Council postdoctoral fellow at the Goddard Institute for Space Studies (New York), he led the proposal efforts for the Cosmic Background Explorer (COBE) (1974–1976) and came to GSFC to be the study scientist (1976–1988), project scientist (1988–1998), and the principal investigator for the Far Infrared Absolute Spectrophotometer (FIRAS) on COBE. He and his team showed that the cosmic microwave background radiation has a blackbody spectrum within 50 parts per million, confirming the Big Bang theory to extraordinary accuracy. As senior project scientist (1995–present) for the James Webb Space Telescope, he leads the science team and represents scientific interests within the project management. He is the recipient of many awards, including the Nobel Prize in Physics (2006) with George Smoot for the COBE work.