Index Key:  PHY066
Author:     delappkc
Subject:    cosmic rays
Text:       What energy range are cosmic rays in are cosmic rays in when they 
hit the earth?  Does the rate of cosmic rays hitting the earth change over 
time , if so how?

Response #:  1 of 2
Author:      A. Smith
Text:        As far as I know, cosmic rays come in just about any energy 
range, up to extremely high energies (higher than anything that can be 
produced in an accelerator on earth).  That is before they hit the atmosphere 
though.  By the time they reach the ground I think most of the high energy 
ones have scattered to produce secondary "showers".  The rate of cosmic ray 
influx does change with time - specifically with the solar cycle.  When the 
sun is active, cosmic rays are not, and vice versa.



Response #:  2 of 2
Author:      John Hawley
Text:        Actually, when the sun is active, it sends out streams of high 
energy protons.  These cause the Aurora borealis in the northern hemisphere 
and present a serious radiation hazard to astronauts.