Historical milestones in cosmic ray astronomy inclue Victor Hess 's discovery of cosmic rays during balloon flights in 1912; the identification of new subatomic particles like the positron and muon in the 1930s, expanding our understanding of particle physics; Pierre Victor Auger 's discovery of extensive particle showers from cosmic ray collisions high in the atmosphere; ground-based detectors measuring cosmic ray flux and energy spectrum in the 1940s-1950s; the establishment of the Volcano Ranch cosmic ray observatory in the 1960s, initiating large-scale experiments; the discovery of cosmic ray anisotropy (the fact that cosmic rays do not arrive uniformly from every region of the sky) in the 1960s, unveiling variations in flux and direction; the emergence of high-energy gamma-ray telescopes in the 1980s-1990s, enabling observations of gamma rays produced by cosmic ray interactions; the advent of space-based detectors like AMS-02 on the International Space Station in the 2000s, providing insights from space; and recent progress in multi-messenger astronomy in the 2010s, integrating cosmic ray observations with other astrophysical signals for a more complete view of cosmic phenomena.