362 FROM NEBULA TO NEBULA 



alone, or at least the two combined, sufficiently suffice to 

 explain the anomaly of the moon's cloudlessness as well 

 as the minor fact that the snow peaks are oftentimes per- 

 ceptibly whiter than their lower, water-soaked slopes. 



ALBEDO. Were the surface of the moon perfectly 

 smooth and covered with new-fallen snow, her albedo (i. 

 e., her general brightness) would far surpass the actu- 

 ality. The deficiency is due to several things, for in- 

 stance ; first, the strong shadows thrown upon her by her 

 own hills, secondly, the slushiness of certain regions, 

 thirdly, the seaming and corrugating of her snow sur- 

 faces due to repeated sopping and irregular settling, and, 

 finally, the darkness of her maria. Paradoxically, her 

 dark side is intrinsically whiter than her illuminated face, 

 for then her maria are covered with fresh sprinkles of 

 snow. 



ABSENCE OF ATMOSPHERIC BEFRACTION. This pecu- 

 liarity has heretofore very properly been attributed to a 

 paucity of air ; some saying that this was carried off by a 

 passing comet; some that it was probably absorbed by 

 porous volcanic rocks ; some that it may have been drawn 

 into the moon's interior by causes unknown ; some that its 

 lighter molecules escaped into space, and still others that 

 the satellite never had any more atmosphere than it has 

 just now. As the reader has already learned, my own 

 view is, that it has been almost totally absorbed by union 

 with the water in the manufacture of snow crystals. 



But there is still another reason. When Prof. Lang- 

 ley invented the bolometer about forty years ago and 

 tested it out on the full moon, he was dumbfounded and 

 disconcerted to find that her heat radiation, instead of 

 being much hotter than at new, is really virtually the 

 same. Nevertheless, he courageously reported the fact 

 as he found it, and was severely ridiculed by no less an 

 authority than the great Proctor himself. Since then, the 

 world of science has been trying to wriggle clear of this 

 evidence; which, however, refuses to down. The sun-lit 

 side of the moon, I reassert, is intensely cold, and, being 



