What are cosmic rays?
Cosmic rays are small rapid projectiles that come from space that bombard the earth. They are not really rays; they are particles. Most cosmic rays are the nuclei of atoms. A lot of them are the nuclei of hydrogen(protons) but some are the nuclei of helium and other nuclei, even lead. Additionally, some are electrons and photons. Also there are secondary cosmic rays that are created by collisions in the atmosphere. These include muons and pions. Scientists are not quite sure where cosmic rays come from but they think they come from stars, supernovas and black holes.

It’s a known fact that cosmic rays move near the speed of light. Cosmic rays have a lot more energy then particles on earth and 100,000,000 times more energy than particles from a particle accelerator. Some particles have even more energy than this and penetrate several kilometers into the earth. Comic rays in nature last longer then the same particles in laboratories on earth. Normally, you can’t see cosmic rays with your eyes. However, they can react in a fashion with certain materials in a way that you can see. They also react with astronomical bodies.