Simplify the following text for a Grade 10 native English-speaking person.
Original: Mather is a Senior Astrophysicist at the NASA Goddard Space Flight Center in Maryland and he is a professor of physics at the University of Maryland , College Park .
Simplified: Mather is a senior astrophysicist at the U.S. space agency 's ( NASA ) Goddard Space Flight Center in Maryland and adjunct professor of physics at the University of Maryland , College Park .