The Romance of the Heavens 41 



Laplace to explain the origin of our solar system, has not yet met 

 with universal acceptance. The explanation offers grave difficul- 

 ties, and it is best while the subject is still being closely investi- 

 gated, to hold all opinions with reserve. It may be taken as 

 probable, however, that the universe has developed from masses 

 of incandescent gas. 



THE BIRTH AND DEATH OF STARS 



3 



Variable, New, and Dark Stars: Dying Suns 



Many astronomers believe that in "variable stars" we have 

 another stay, following that of the dullest red star, in the dying 

 of suns. The light of these stars varies periodically in so many 

 days, weeks, or years. It is interesting to speculate that they 

 are slowly dying suns, in which the molten interior periodically 

 bursts through the shell of thick vapours that is gathering round 

 them. What we saw about our sun seems to point to some such 

 stage in the future. That is, however, not the received opinion 

 about variable stars. It may be that they are stars which periodi- 

 cally pass through a great swarm of meteors or a region of space 

 that is rich in cosmic dust of some sort, when, of course, a great 

 illumination would take place. 



One class of these variable stars, which takes its name from 

 the star Algol, is of special interest. Every third night Algol 

 has its light reduced for several hours. Modern astronomy has 

 discovered that in this case there are really two stars, circulating 

 round a common centre, and that every third night the fainter 

 of the two comes directly between us and its companion and 

 causes an "eclipse." This was until recently regarded as a most 

 interesting case in which a dead star revealed itself to us by pass- 

 ing before the light of another star. But astronomers have in 

 recent years invented something, the "selenium-cell," which is 

 even more sensitive than the photographic plate, and on this the 



