“Yes,” replied Barbicane, “after having doubtless remained persistently for millions of centuries; by degrees the atmosphere becoming rarefied, the disc became uninhabitable, as the terrestrial globe will one day become by cooling.”
“By cooling?”
“Certainly,” replied Barbicane; “as the internal fires became extinguished, and the incandescent matter concentrated itself, the lunar crust cooled. By degrees the consequences of these phenomena showed themselves in the disappearance of organized beings, and by the disappearance of vegetation. Soon the atmosphere was rarefied, probably withdrawn by terrestrial attraction; then aerial departure of respirable air, and disappearance of water by means of evaporation. At this period the moon becoming uninhabitable, was no longer inhabited. It was a dead world, such as we see it to-day.”
“And you say that the same fate is in store for the earth?”
“Most probably.”
“But when?”
“When the cooling of its crust shall have made it uninhabitable.”
“And have they calculated the time which our unfortunate sphere will take to cool?”
“Certainly.”
“And you know these calculations?”