OSA Honorary Member John C. Mather is a Senior Astrophysicist in the Observational Cosmology Laboratory at NASA's Goddard Space Flight Center. His research centers on infrared astronomy and cosmology.

As an NRC postdoctoral fellow at the Goddard Institute for Space Studies (New York City), he led the proposal efforts for the Cosmic Background Explorer (74‐76), and came to GSFC to be the Study Scientist (76‐88), Project Scientist (88‐98), and also the Principal Investigator for the Far IR Absolute Spectrophotometer (FIRAS) on COBE. He showed that the cosmic microwave background radiation has a blackbody spectrum within 50 ppm. As Senior Project Scientist (95‐present) for the James Webb Space Telescope, he leads the science team, and represents scientific interests within the project management. He has served on advisory and working groups for the National Academy of Sciences, NASA, and the NSF (for the ALMA, the Atacama Large Millimeter Array, and for the CARA, the Center for Astrophysical Research in the Antarctic). He has received many awards including the Nobel Prize in Physics, 2006, for his precise measurements of the cosmic microwave background radiation using the COBE satellite.

He is a Fellow and Honorary Member of The Optical Society, a Fellow of the American Academy of Arts and Sciences, the American Physical Society and SPIE.  In 2016, he was named an honorary member of the Optical Society "for measuring, with his COBE team, the cosmic background radiation and its anisotropy with amazing precision from 50 to 600 GHz. The temperature of the Big Bang radiation was determined as 2.725 +/‐ 0.001K. According to the Nobel committee the COBE project can be regarded as the starting point of cosmology as a precision science."