238 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1957 



journey at the sun arrived in the vicinity of the earth at first in the 

 direction from the sun — that is, after one takes into account the 

 local effects of the earth's magnetism — but later on during the decline 

 they arrived quite certainly from other directions. Now there is no 

 other effect that could have deflected these fast particles from a 

 straight-line path except suitable' magnetic fields in the space of the 

 solar system. 



What are the shapes of such magnetic fields ? How can one account 

 for the curious fact that the stream can evidently reach here in the 

 first place without deflection, but that the latecomers get deflected? 

 This and a number of other effects are at the present time under dis- 

 cussion. Naturally one wants to learn as much as possible about 

 the conditions in the solar system before one can go up and have a 

 look. 



I have been discussing these problems with colleagues at Cornell 

 University, and with Dr. Hayakawa from Japan, and we conclude 

 that the effects would be reproduced if we supposed that the outer 

 corona of the sun extended to the earth, and that it retained the 

 streamerlike appearance. "We therefore considered the propagation 

 of cosmic-ray particles along very elongated "streamers" of magnetic 

 field. The particles will then spiral around the direction of the 

 field, and the ones that were accidentally emitted just in the direction 

 will be the first to arrive ; the ones that started at an angle will take 

 a longer path and hence arrive later. The last to arrive will then be 

 those that started in extremely flat spirals, and those will then appear 

 to arrive at the earth from directions other than that to the sun. Now 

 this was just what happened. On this basis we then calculate the 

 way in which the intensity would rise and fall, owing to the delay 

 effect of the spirals, and the agreement is good. There are still 

 some points that need further explanation, but I feel sure that we 

 are here learning something about the conditions in the solar system. 



Much of the difficulty of the discussion would be removed if only 

 the sun were kind enough to give us another event of this sort. I am 

 certainly hoping for one. But perhaps one day this sort of thing 

 will be regarded as one of the hazards of space flight, for without 

 the protection of the thick atmosphere these effects may be quite 

 unhealthy. Then we shall be glad that they are so rare. 



