@sciencesage: The last video you all found out about the flashes of light that astronauts see inside their eyes, which aren't light, but sometimes light made in their eyes. Lot's of questions happened, so this is to explain all those questions. How do energized particles get into the spaceship? What are energized particles? What are cosmic rays? Is it safe? How does it cause cancer? I hope this answers everyone's questions; if not, as always, I try to answer #Science #space #astronauts #followup #apollo #cosmicrays