ALIEN EARTHS

A leading astronomer blends knowledge and enthusiasm to show how the universe is slowly being revealed.

This book is an excursion that turns the esoteric field of stellar cartography into an engaging and entertaining story. Kaltenegger, the director of the Carl Sagan Institute at Cornell, has a knack for starting with a few simple principles and then adding layers of increasing complexity. She believes the discipline of astronomy is at a turning point, mainly due to the new NASA James Webb Space Telescope, which has provided a new level of stargazing clarity and distance. The revolutionary telescope has led to new ways “to explore the universe around us by reading the message encoded in light,” a process that Kaltenegger explains in jargon-free terms. Information gleaned from spacecraft travel has also been valuable. Scientists have discovered a host of exoplanets, and the author looks at a handful that could harbor some form of life. She also examines possibilities in our own solar system, with Mars and the moons Titan, Europa, and Enceladus being contenders in the search for organisms—although they would probably be microbial. Kaltenegger clearly loves her subject and often injects flashes of dry wit and personal experience. She devotes a chapter to planets that have appeared in science fiction, having some fun with probabilities and impossibilities. She likes to think that there’s intelligent life somewhere out there, but she admits that the hunt has yet to yield positive results. Regardless, humanity has so far barely scratched the surface of the galaxy. A bonus of the book is an appendix of websites offering further information and even the opportunity for citizen scientists to propose names for new exoplanets.

Kaltenegger’s exploration of nearby and faraway space is absorbing, informative, and entertaining.