Hold out your hand for 10 seconds. A dozen electrons and muons just zipped unfelt through your palm. The ghostly particles are what scientists call secondary cosmic rays. Subatomic debris from collisions between molecules high in Earth’s atmosphere and high-energy cosmic rays from outer space.
This daily shower, which never stops, is a sign of violent events in deep space.
It’s believed that the majority of cosmic rays come from supernova explosions. When massive stars explode they blast most of their material into space. The expanding shock waves can break apart interstellar atoms and accelerate the debris to unimaginably high energies.
