Worlds Without End

Planet Earth may be far from the ideal home we once assumed. Humans are using up its resources, wiping out species, and wearing down the conditions that sustain life. Meanwhile, progress in finding habitable worlds has gone well beyond early hopes of settling Mars. This book follows the search for planets that could support life, and the possibility that people might one day live on one.

Chris Impey, a writer known for accessible books about astronomy and space science, guides readers through astrobiology, a field that is advancing quickly. He surveys recent breakthroughs that bring the discovery of life elsewhere closer, along with the prospect of people settling on another planet. The story starts in 1995, when the first planet orbiting a star beyond our solar system was found. Since then more than 4,000 others have been identified. Hundreds of them are Earth-like, and many are habitable, with numerous detections made by the Kepler satellite.

The book draws on astronomy, planetary science, geology, chemistry and biology to explain what drives this rapid progress, what may come next, and what it could mean for humanity's future. Existential threats on Earth give the search added urgency, and the central question is whether space might ultimately save us.

Along the way, Impey examines what habitability actually means and how space exploration is changing as private companies take on roles once held mainly by governments. The science he presents points toward answers both near and far.