With Dr. Kaltenegger as our witty and knowledgeable tour guide, we discover not merely new continents, like the explorers of old, but whole new worlds circling other stars. This riveting account will appeal to anyone who has ever gazed at the night sky in wonder.
ALIEN EARTHS
The New Science of Planet Hunting in the Cosmos
by Lisa Kaltenegger
St. Martin’s Press, April 2024
For thousands of years, humans have wondered whether we are alone in the cosmos. Now, for the first time, we have the technology to investigate. The question should have an obvious answer: yes or no. But once you try to find life elsewhere, you realize it is not so simple. What is life, actually? How do you find it over cosmic distances? And where are we the aliens? As director of the Carl Sagan Institute at Cornell University, astronomer Lisa Kaltenegger works with teams of tenacious scientists building the uniquely specialized tool kit to find life on alien worlds. In Alien Earths, she provides an insider’s view of what scientists are learning from Earth’s history and its astonishing biosphere. With an infectious enthusiasm, she takes us on an eye-opening journey to a dozen of the most unusual exoplanets that have shaken our worldview—planets covered in oceans of lava, lonely wanderers lost in space, and planets with more than one sun in the sky! And she dives into the worlds of science fiction, using these imagined other worlds to entertainingly describe how close they come to reality. With the James Webb Space Telescope, other smaller telescopes, and the pioneering work that Dr. Kaltenegger is carrying out in her labs, we live in an incredible epoch of exploration.
Lisa Kaltenegger is the Director of the Carl Sagan Institute to Search for Life in the Cosmos at Cornell and Associate Professor in Astronomy. She is a pioneer and world-leading expert in modeling potential habitable worlds and their detectable spectral fingerprint. Kaltenegger serves on the National Science Foundation’s Astronomy and Astrophysics Advisory Committee (AAAC), and on NASA senior review of operating missions. She is a Science Team Member of NASA’s TESS Mission as well as the NIRISS instrument on James Webb Space Telescope. Kaltenegger was named one of America’s Young Innovators by Smithsonian Magazine, an Innovator to Watch by TIME Magazine.

A population calamity is unfolding before our eyes. It started in parts of the developed world and is spreading to the four corners of the globe. There are just too few babies being born for humanity to replace itself. Before the end of the current century at the latest, and probably much sooner, the world’s population will start to decline.
Ask anyone on Atbara Avenue how well they know their neighbours, and they’ll answer ‘well’.
Haeni’s family falls apart after her older sister dies in a gas explosion accident in 1994. Unable to salvage the marriage, Haeni’s mother decides to separate from her father, and immigrates to Germany with Haeni and her younger sister.