cosmic rays

plural noun

1. radiation consisting of particles, esp protons, of very high energy that reach the earth from outer space Also calledcosmic radiation

cosmic rays

1. Elementary particles , mainly protons , that are produced by the sun and other stars and then strike the upper atmosphere of the Earth . Some of these particles are absorbed, some help form the Van Allen belt , and some reach the Earth's surface, where they form a part of the background radiation that constantly surrounds us.