THE EDGE OF THE SUN — MENZEL 227 



tified surges seen at the limb as true flares, so that the flare is by no 

 means restricted to the loop form. 



I wish to point out that a new technique is rapidly contributing 

 knowledge about the sun and solar activity : the so-called field of radio 

 astronomy. Time and space do not permit detailed discussion of the 

 phenomenon. However, it is certain that simultaneous optical and 

 radio observations will give important information about solar ac- 

 tivity at various levels in the sun's atmosphere, especially since the 

 lower frequencies can escape only from the higher, more tenuous 

 coronal regions. We are still finding out important facts and con- 

 clude that the edge of the sun well deserves the attention that scien- 

 tists are currently devoting to this subject. 



Reprints of the various articles in this Report may be obtained, as long as 

 the supply lasts, on request addressed to the Editorial and Publications 

 Division, Smithsonian Institution, Washington 25, D. C. 



