SECRETARY'S REPORT 69 



One of the long-term goals of the Astrophysical Observatory is to 

 conduct astronomical observations and experiments above the atmos- 

 phere and to develop relevant techniques of value to the research pro- 

 gram. When this goal has been attained, we shall not only improve 

 vastly the precision and significance of our observations by eliminat- 

 ing the deleterious effects of a hazy, cloudy, turbulent, and mostly 

 opaque atmosphere but also greatly increase our understanding of the 

 interactions, because the external energy sources affect profoundly 

 this ocean of atmosphere in which we live. 



Solar astrophysics. — Early in the fiscal year, Dr. Theodore E. 

 Sterne joined the Astrophysical Observatory as Associate Director, 

 with the principal duty of supervising solar astrophysical research. 

 The following are among the studies that have been pursued in this 

 field: 



The Table Mountain station continued to operate despite atmos- 

 pheric disadvantages outlined in the 1956 report. Of the observing 

 staff, F. A. Greeley retired during the year, and Stanley Aldrich went 

 on leave of absence at the end of the year. 



Careful statistical studies of the variation of solar radiation inten- 

 sity were made by Dr. Sterne and by Mrs. Nannielou Dieter, who 

 joined the Observatory for the summer of 1956. By comparing simul- 

 taneous Montezuma and Table Mountain values between 1926 and 1955, 

 they found that the root-mean-square value of real changes in the 

 solar constant during this interval was no greater than 0.0032 calorie 

 per square centimeter per minute, or about 0.17 percent of the solar 

 constant itself. This result demonstrates the high precision of the 

 fundamental observations made over the years. They also calculated 

 correlations from the observations at each station separately and found 

 no periodicities that were common to the two stations. 



A thorough study is being made for the improvement of the radia- 

 tion-measuring program by changes in the site, the observing equip- 

 ment, and the frequency of observations. 



Dr. Max Krook has been investigating the theory of nonsteady phe- 

 nomena in the solar atmosphere and corona. His studies include the 

 effects of convective instabilities and magnetic fields on the state of 

 motion of the solar atmosphere, and have shed light on the production 

 of such events as sunspots, flares, prominences, and the production of 

 cosmic rays. 



Theoretical studies of the propagation of nonadiabatic acoustic 

 waves in the solar atmosphere have been made by Dr. Charles Whitney, 

 who joined the staff in July 1956. He has succeeded in constructing 

 a theoretical model for solar granulation (small-scale brightness fluc- 

 tuations observed on the solar disc) which is in accord with observa- 

 tions. Although such studies have been made with particular empha- 

 sis on solar activity, they will have a much wider application. 



