Page:The evolution of worlds - Lowell.djvu/38

16 What was this ejectum and what drove it forth? Professor Very regarded it as composed of corpuscles such as give rise to cathode rays discharged from the star under the stress of light pressure or electric repulsion. But I think we may see in it something simpler still; to wit, gaseous molecules driven off by light pressure alone—the smoke, as one may say, of the catastrophe—akin exactly to the constituents of comet's tails. The mere light of the conflagration pushed the hydrogen molecules away. This would explain their presence and their exceeding hurry at the same time. They were started on their travels by domestic jars and kept going by the vivid after-effects of that infelicity.

The fairly steady rate of regression from the nova observed may be explained by the observed decrease in the light of the repellent source. Such combined with the retarding effect of gravity might make the regression equable. This is the more explanatory as the speed was certainly much less than that of light, though greatly exceeding any possible from the direct disruption. At the same time both the bright and the dark lines of hydrogen seen in the spectrum stand accounted for; the colliding molecules, at their starting on their travels from the star, shining through their sparser fellows farther out. An interesting biograph of the levity of light!