Cosmic rays from space are all around you and passing through your body all the time, but you'll never see or feel them. You can see evidence of them, however, in our Cloud Chamber exhibit: wispy lines show the paths of tiny, high-energy particles generated by cosmic rays. Cloud Chamber was one of the Exploratorium's very first exhibits, acquired on loan from NASA Ames Research Center in the summer of 1969; it was originally built at the Lawrence Berkeley Laboratory for demostration purposes.