Andrea Lefebvre,, age ,12.; of Niagara Falls, Ontario, Canada, for her question:

Where do cosmic rays come from?

Our planet is under continuous bombardment from space. No, we are not under attack from hostile aliens. The infinitesimal bullets are ,the nuclei of atoms traveling at tremendous speeds. Their speeds give them dangerous penetrating power, but fortunately these missiles from afar do not reach the surface of the earth. As they crash through our atmosphere they shatter themselves apart in collisions with  gaseous molecules of, the sir. The fragments of these collisions are somewhat slower and less penetrating., They continue down , to   the surface and piercing  deep in to the ground.

The particles that come from afar; are primary cosmic rays.: Most of them are .. ions  of  hydrogen and helium atomic nuclei stripped of their electrons. Some come from solar, flares and other nuclear upheavals on the sum. Others are thought to come from far out in space beyond the solar system, perhaps from remote cosmic explosions. The secondary cosmic rays that strike the surface of the earth are atomic fragments from shattered primary rays and air molecules