We report evidence of the first astrophysical source detected from the Moon. Our detection of Cygnus X-1 is a validation of a new investigative paradigm in which the lunar environment is intrinsic to the detection approach: the Lunar Occultation Technique (LOT). NASA’s Lunar Prospector mission served as a proxy for a dedicated LOT-based mission. The characteristic signature of temporal modulation, generated by repeated lunar occultations and encoded within acquired gamma-ray data (0.5-9 MeV), is consistent with an unambiguous detection of Cygnus X-1. This “first light” detection is a demonstration of the basic tenets of the LOT methodology, reinforces its feasibility as an alternative astronomical detection paradigm, and is an illustration of the fundamental benefits of the Moon as a platform for science.