The life and death of planet earth: how the new science of astrobiology charts the ultimate fate of our world

It is the year 7 billion A.D. The sun has gone into its red giant phase. The Earth has been consumed by the outer envelope of the 100-million-mile-diameter sun. Mars is a dried and lifeless body with a surface temperature sufficient to melt its crustal rocks. Jupiter is a roiling, heater mass rapidly losing gas and material to space. The ice cover of Jupiter’s moon Europa has long since melted away, followed by the disappearance of its oceans to space. Farther away, Saturn has lost its icy rings. But once world of this vast solar system has benefited from the gigantic red orb that is the Sun. It is Saturn’s largest moon, aptly named Titan.

Long before, in the time of humanity, a science fiction writer named Arthur C. Clarke penned a series of tales about the moon of Jupiter named Europa. In these stories, alien beings somehow turned Jupiter into a small but blazing star, and in so doing warmed Europa—and brought about the creation of life. A wonderful, though physically impossible, fable. Now, in these late days of the solar system, the huge red Sun was doing the same to Titan, changing it from frozen to thawed, and in so doing liberating the stuff of life. But Titan was always a very different world than Europa. Like Europa, Titan always had oceans. Frozen, to be sure, but oceans nevertheless. But where Europan oceans were water, those of Titan were of a vastly different substance—ethane. Titan had always been covered with a rich but cold stew of organic materials. And with the coming of heat, for the first time Eden came to Titan. Like a baby born to an impossibly old woman, life came to this far outpost, the last life ever to be evolved in the solar system.

The red giant phase was short-lived—only several hundred million years, in fact. But it was enough. For a short time, for the last time, life bloomed in the solar system. After death, once more came the resurrection of life in masses of tiny bacteria like bodies on a moon once far from a habitable planet called Earth, a place that, in its late age, evolved a species with enough intelligence to predict the future, and be able to prophesize how the world would end.