In 1969, Apollo 11 astronauts saw mysterious flashes with their eyes closed. Scientists later found the cause

During the Apollo missions, astronauts noted peculiar flashes of light occurring inside their spacecraft. These experiences were later attributed to energetic cosmic rays penetrating their vision. NASA played a pivotal role in investigating these occurrences, establishing a firm link between the light flashes and cosmic radiation. This foundational work is vital for preparing future astronauts against the hazards of long-duration space exploration.