When the Moon Darkens the Sun 



What astronomers will look for during the June total eclipse of the Sun 



Bv ('al\in Fr;iZ(M- 



A TOTAL eclipse of the sun is one 

 of the most awe-inspiring spec- 

 tacles in the whole repertory of 

 Nature. Its overpowering effect upon 

 the human mind is illustrated by an 

 episode which the present writer recalls 

 in connection with the eclipse of May 

 28, 1900, as seen 

 at Norfolk, Vir- 

 ginia. The weather 

 was superb, and the 

 town was crowd- 

 ed with visitors: 

 besides whom the 

 natives were all on 

 the streets. During 

 the period of about 

 an hour following 

 "first contact," 

 while the disk of the 

 moon encroached 

 more and more 

 upon the face of 

 the sun, the spec- 

 tators, white and 

 black, kept up a 

 lively chatter of 

 conversation. 

 Probably most of 

 them found the 

 phenomenon 

 rather tame, and wondered why people 

 should travel miles to see it. Just be- 

 fore the beginning of totality the light 

 of day faded with startling abruptness, 

 the beautiful solar corona flashed out, 

 the stars appeared in the sky, and a 

 ruddy glow, as of late sunset, encircled 

 the horizon. The babel of conversation 

 ceased instantly, and was succeeded by 

 the crash of breaking glass. Totally un- 

 prepared for so marvelous a sight, many 

 people, especially among the colored 

 population, let fall the pieces of smoked or 

 tinted glass through which they had been 

 \iewing the eclipse! 



Interesting to the layman as a spec- 

 tacular event, a total solar eclipse is 

 even more interesting to the astronomer 

 as a rare opportunity for obtaining fresh 



Renewed efforts will be ir.c^c qL liic com- 

 ing eclipse to solve the mystery of the 

 flickering "shadow bands," which steal 

 over the ground at the beginning and end 

 of totality. Former attempts to photo- 

 graph these "flickerings" were not successful 



light on a wide range of scientific prob- 

 lems. Hence, in order to observe a proc- 

 ess of Nature lasting generally only two 

 or three minutes e.xpeditions are or- 

 ganized and equipped at great expense, 

 and sent perhaps halfway 'round the 

 world to some favorable vantage point. 

 After arrival, many 

 weeks are spent in 

 setting up and ad- 

 justing instruments 

 and rehearsing 

 every detail of the 

 observations, so 

 that the advance 

 program may be 

 carried out with- 

 out a hitch at the 

 proper time. Every 

 precaution is ta- 

 ken to economize 

 to the utmost the 

 precious seconds 

 available during 

 the event. 



After all these 

 preparations, the 

 astronomers in 

 many cases get no 

 results at all, ow- 

 ing to unfavorable 

 weather. A single cloud may blast their 

 hopes. The party sent from the Lick 

 Observatory to view the eclipse of 1900 

 encountered a citizen of Georgia who 

 was frankly skeptical about their ability 

 to foretell the occurrence of the eclipse, 

 and his doubts deepened to positive dis- 

 belief when he heard the observers 

 anxiously speculating about what the 

 state of the weather might be on the 

 eventful day. "These young men," he 

 said, "try to tell me they know the sun 

 is going to be eclipsed, and they can't 

 even tell whether the sky is going to be 

 clear!" 



fnfortunately the only help the mete- 

 orologist can give to the astronomer in 

 this matter is to tell him what the average 

 weather has been in previous years on the 



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