Rodger Wehage, age 12, of Portland, Ore., for his question:
Where do cosmic rays come from?
Our poor old world, it seems, is at war with the entire universe. Day and night it is bombarded with barrages of bullets from outer space. Some of this heavenly artillery is called cosmic rays and may well come from the farthest parts of the Milky Way.
In the language of science, a ray can be a stream of electromagnetic energy, such as a radio wave. A ray is also the name of a stream of electrically charged particles, such as the electrons which draw the picture on a TV screen. Cosmic rays are streams of high speed particles which crash into the lofty atmosphere above the earth.
These bullets from outer space may reach almost the speed of light. They are the cores or nuclei of atoms with the outer electrons stripped away. Such lopsided atoms are charged ions and most of the cosmic rays which hit the upper atmosphere are ions of light weight atoms such as hydrogen and helium. A few are ions of the heavier atoms oxygen, carbon and neon.
These space travelers that plunge into the upper atmosphere are called primary cosmic rays. With reckless speed they now collide with gas molecules of the air. Some of their speed energy is lost with each traffic accident, but particles are shorn from the air molecules and sent flying in all directions.
The primary cosmic rays never reach the earth, but fragments from their traffic accidents come plunging down as secondary cosmic rays. Day and night, the earth is struck with a steady barrage of speeding electrons, protons and other atomic particles from collisions between air molecules and bullets from outer space.
Streams of atomic particles reach the earth from the sun, especially after a display of solar flares or other sunspot activity.
But the particles of cosmic rays are much faster and the barrage comes steadily from all directions. For those reasons, science assumes that they come from outer space though we are far from certain about their origin.
Outer space contains a lot of drifting star dust. Vast clouds of hazy gas and debris hover in the Milky Way and sometimes a star explodes, tossing its gases in all directions. Some of these gaseous fragments may get trapped between cosmic magnetic fields, tossed back and forth and whipped to furious speeds. This dramatic event may or may not be the source of our cosmic rays.
We have two good reasons for seeking the truth about these cosmic bullets. Space travelers must cope with primary cosmic rays and secondary cosmic rays bombarding everything on earth. On the spot information is gathered by some of our satellites and sent down to be analyzed. Several satellites are still orbiting after their work is done.