New observations seem to settle the question of where cosmic rays come from. Dr Tony Padilla discusses the research. See the paper at: http://arxiv.org/pdf/1302.3307v1.pdf COMMENT FROM TONY: "My comments at 1.30 were a bit hasty. Cosmic rays do not pass through the earth. Most collide in the upper atmosphere. I was actually thinking of the LHC safety debate. If they exist, mini blackholes produced by cosmic ray collisions on earth would slip straight through because the earth isn't dense enough. But not the protons themselves." Tony tweets at https://twitter.com/DrTonyPadilla (lots of good science news, links and jokes mixed with some over emotional football commentary) Nasa write-up at: http://www.nasa.gov/home/hqnews/2013/feb/HQ_13-052_FERMI_Supernova.html Visit our website at http://www.sixtysymbols.com/ We're on Facebook at http://www.facebook.com/sixtysymbols And Twitter at http://twitter.com/#!/periodicvideos This project features scientists from The University of Nottingham http://www.nottingham.ac.uk/physics/index.aspx Sixty Symbols videos by Brady Haran A run-down of Brady's channels: http://periodicvideos.blogspot.co.uk/2012/06/here-are-my-channels.html