cosmic rays: Elementary atomic
particles (such as electrons and
protons) or atomic nuclei that are
highly energized and travel through
space at close to the speed of light.
These particles are generally absorbed
by Earth’s atmosphere. Cosmic rays
are easily detected on Earth and are
related to a number of astronomical
phenomena, but the process that
produces them is still a matter of
scientific debate. According to one
common theory, cosmic rays are born
during the tremendous supernova
explosions of massive dying stars. If
this theory is true, cosmic rays should