John Francis Kielkopf is an American astrophysicist living in Louisville, Kentucky, where he was born in 1945. He received his doctorate in physics from Johns Hopkins University in 1969, and then joined the faculty of the University of Louisville where he is a professor of physics and astronomy. Known for his early work on atomic collisions and spectra, his current research is about the detection and characterization of extrasolar planets, and the applied science of remote optical sensing. He also develops open resources for physics and astronomy education.
His wife Helen Kielkopf created Hidden Hollow Orchard where she cultivates antique apple varieties and they care for rescued and retired horses. Their daughter, Clara Kielkopf, is a professor of biochemistry and biophysics at the University of Rochester Medical Center.