Jonathan Christopher McDowell, born on July 6, 1960, is a British-American astrophysicist working at the Harvard–Smithsonian Center for Astrophysics's Chandra X-ray Center. He is known for his research on black holes, quasars, and X-ray sources in distant galaxies. McDowell also develops software tools utilized by astronomers globally. Since 1989, he has authored and edited Jonathan's Space Report, a newsletter that documents satellite launches and space activities. His work often corrects official sources and provides additional data on classified launches.
McDowell's contributions include designing the CIAO data analysis package and software infrastructure for the Chandra X-ray Observatory. He has also led the creation of astronomical image exhibits at the Smithsonian. In 1994, he suggested that 80 kilometers be adopted as the boundary of space. Furthermore, McDowell has been involved in discussions surrounding space junk and space policy. As of late January 2026, he noted there were 14,518 active payloads in Earth orbit, with 9,555 belonging to Starlink. In 2025, McDowell expressed concerns about the future of science in the U.S. and announced his departure from the Harvard Observatory.
