113 PLEASANT WAYS IN SCIENCE. 



phenomena. But, as actually advanced, neither seems 

 satisfactory. The sudden pouring forth of hydrogen from 

 the interior, in quantities sufficient to explain the outburst, 

 seems altogether improbable. On the other hand, as I 

 have pointed out elsewhere, there are reasons for rejecting 

 the theory that the cause of the heat which suddenly affected 

 this star was either the downfall of a planet on the star or 

 the collision of the star with a star-cloudlet or nebula, 

 traversing space in one direction, while the star rushed 

 onwards in another. 



A planet could not very well come into final conflict 

 with its sun at one fell swoop. It would gradually draw'" 

 nearer and nearer, not by the narrowing of its path, but by 

 the change of the path's shape. The path would, in fact, 

 become more and more eccentric ; until at length, at its 

 point of nearest approach, the planet would graze its 

 primary, exciting an intense heat where it struck, but 

 escaping actual destruction that time. The planet would 

 make another circuit, and again graze the sun, at or near 

 the same part of the planef s path. For several circuits this 

 would continue, the grazes not becoming more and more 

 effective each time, but rather less. The interval between 

 them, however, would grow continually less and less ; at last 

 the time would come when the planet's path would be 

 reduced to the circular form, its globe touching the sun's 

 all the way round, and then the planet would very quickly 

 be reduced to vapour and partly burned up, its substance 

 being absorbed by its sun. But all successive grazes would 

 be indicated to us by accessions of lustre, the period between 

 each seeming outburst being only a few months at first, and 

 gradually becoming less and less (during a long course of 

 years, perhaps even of centuries) until the planet was 

 finally destroyed. Nothing of this sort has happened in the 

 case of any so-called new star. As for the rush of a star 

 through a nebulous mass," that is a theory which would 

 scarcely be entertained by any one acquainted with the 

 enormous distances separating the gaseous star-clouds 



