CHAPTER VI. 



THE APPEARANCE OF THE CORONA. 



WE cannot but regard it as a strange circumstance that 

 there is so seldom any mention of the Corona in the 

 records of ancient eclipses. It is often mentioned that " the 

 stars appeared as. in the night-time," though we know from 

 the experiences of recent years that few stars other than the 

 brightest planets ever become visible on such occasions. But 

 the corona, so beautiful an object and of such strange and 

 mysterious shape, larger than the moon, and often much brighter 

 than the moon when full, is scarcely ever unmistakably alluded 

 to. Plutarch is generally held to have referred to it in a well- 

 known passage describing a total eclipse, and Philostratus in 

 Iris life of Apollonius of Tyana; whilst a "red light" which 

 was seen round the dark moon, during the solar eclipse which 

 took place during the battle of Sticklastad in Norway, in 1030, 

 August 31, is generally thought to have been the corona, but 

 may have been a brilliant display of prominences. In more 

 modern times we have a few explicit and definite accounts, 

 ranging from the observations of Clavius, 1567, April 9, down 

 to those of the eclipse of 1842, July 8, from which time the 

 corona has been the subject of careful and attentive study ^ 



The explanation of this strange omission of the corona from 

 nearly all the old accounts, whilst the appearance of the stars is 

 so frequently noticed, is probably that the old observers knew 

 that the stars ought to appear, and therefore looked for them, 

 and in consequence saw them. But they did not expect to see 

 the corona, and if they did notice it very likely thought it a 

 mere diffusion of the sun's light from behind the moon, just as 

 we see the sun's rays lighting up the dusty or moisture-laden air 

 when the sun itself is hidden behind a cloud, whether due to the 

 effect of an atmosphere round the moon, or to a scattering in 

 the higher regions of the earth's atmosphere, or to a sort of 

 diffraction effect at the moon's limb. Each of these three 

 explanations has been widely accepted in its turn ; that which 

 ascribes the corona to the scattering of the sun's light by our 

 own atmosphere being strongly held by some even as late as 

 1870. 



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