Lonely Planets

It's been nearly four decades since Carl Sagan first addressed the general public from a scientist's perspective, confronting the possibility of extraterrestrial life. David Grinspoon, a planetary scientist who has helped to shape modern planetary exploration, brings the subject to a new generation of readers with his reflections on the most recent developments in astrobiology, including NASA's search for life on Mars. In Lonely Planets, he investigates the big questions: How widespread are life and intelligence in the cosmos? Is life on Earth an accident or in some sense the "purpose" of…