Are alien civilizations really possible? If extraterrestrials exist, where are they? How likely is it that somewhere in the universe an Earth-like planet supports an advanced culture? Why do so many people claim to have encountered Aliens? In this gripping exploration, scientist Don Lincoln exposes and explains the truths about the belief in and the search for life on other planets. In the first half of Alien Universe, Lincoln looks to Western civilization's collective image of Aliens, showing how our perceptions of extraterrestrials have evolved over time. The roots of this belief can be traced as far back as our earliest recognition of other planets in the universe—the idea of them supporting life was a natural progression of thinking that has fascinated us ever since. Our captivation with Aliens has, however, led to mixed results. The world was fooled in the nineteenth century during the Great Moon Hoax of 1835, and many people misunderstood Orson Welles's 1938 radio broadcast, The War of the Worlds, leading to significant anxiety among some listeners. Our continuing interest in Aliens is reflected in entertainment successes such as E.T., The X-Files, and Star Trek. The second half of the book explores the scientific possibility of whether advanced Alien civilizations do exist. For many years, researchers have sought to answer Enrico Fermi’s great paradox—if there are so many planets in the universe and there is a high probability that many of those can support life, then why have we not actually encountered any Aliens? Lincoln describes how modern science teaches us what is possible and what is not in our search for extraterrestrial civilizations. Whether you are drawn to the psychological belief in Aliens, the history of our interest in life on other planets, or the scientific possibility of Alien existence, Alien Universe is sure to hold you spellbound.

Originally published in Great Britain by Profile Books Ltd, 2016.

PEN Literary Award Winner: “The best, most entertaining examination of the possibility of other life in the universe since [Carl] Sagan’s best work.” —Boulder Daily Camera It’s been decades since Carl Sagan first addressed the general public about the possibility of extraterrestrial life from a scientist’s perspective. We’ve learned a lot in those years, and now planetary scientist David Grinspoon 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 this universe? And how can we, working from the Earth-centric definition of “life,” even begin to think about the varieties of life-forms on other planets? In accessible, lively prose, and using the topic of extraterrestrial life as a mirror with which to view human beliefs, evolution, history, and aspirations, Grinspoon takes us on a three-part journey—the history of our expanding awareness of other planets and our ideas on alien life dating back to the earliest days of astronomy; the science of cosmic evolution and the evolution of life on Earth, including a critique of the “Rare Earth hypothesis”; and the beliefs that humans hold, addressing the limits of our ability to conceptualize or communicate with intelligent aliens and the scientific and philosophical implications of far-future evolutionary possibilities. Rich in personal and often amusing anecdotes, Lonely Planets explores the shifting boundary between planetary science and natural philosophy, and reveals how the search for extraterrestrial life unites our spiritual and scientific quests for connection with the cosmos. Includes a new foreword about recent Mars discoveries “An outstanding introduction to cosmic evolution.” —San Jose Mercury News “[A] terrific book.” —San Diego Union-Tribune “A personable chat on life, the universe and everything.” —Publishers Weekly

The field of planetary biology and chemical evolution draws together experts in astronomy, paleobiology, biochemistry, and space science who work together to understand the evolution of living systems. This field has made exciting discoveries that shed light on how organic compounds came together to form self-replicating molecules-the origin of life. This volume updates that progress and offers recommendations on research programs-including an ambitious effort centered on Mars-to advance the field over the next 10 to 15 years. The book presents a wide range of data and research results on these and other issues: The biogenic elements and their interaction in the interstellar clouds and in solar nebulae. Early planetary environments and the conditions that lead to the origin of life. The evolution of cellular and multicellular life. The search for life outside the solar system. This volume will become required reading for anyone involved in the search for life's beginnings-including exobiologists, geoscientists, planetary scientists, and U.S. space and science policymakers.

New York Times Bestseller | Wall Street Journal Bestseller | Publishers Weekly Bestseller | Publishers Marketplace 2020 Buzz Book | Amazon Best Book of the Year | Longlisted for the 2022 PEN/E.O. Wilson Literary Science Writing Award “Provocative and thrilling ... Loeb asks us to think big and to expect the unexpected.” —Alan Lightman, New York Times bestselling author of Einstein’s Dreams and Searching for Stars on an Island in Maine Harvard’s top astronomer lays out his controversial theory that our solar system was recently visited by advanced alien technology from a distant star. In late 2017, scientists at a Hawaiian observatory glimpsed an object soaring through our inner solar system, moving so quickly that it could only have come from another star. Avi Loeb, Harvard’s top astronomer, showed it was not an asteroid; it was moving too fast along a strange orbit, and left no trail of gas or debris in its wake. There was only one conceivable explanation: the object was a piece of advanced technology created by a distant alien civilization. In Extraterrestrial, Loeb takes readers inside the thrilling story of the first interstellar visitor to be spotted in our solar system. He outlines his controversial theory and its profound implications: for science, for religion, and for the future of our species and our planet. A mind-bending journey through the furthest reaches of science, space-time, and the human imagination, Extraterrestrial challenges readers to aim for the stars—and to think critically about what’s out there, no matter how strange it seems.

The search for life in the solar system and beyond has to date been governed by a model based on what we know about life on Earth (terran life). Most of NASA's mission planning is focused on locations where liquid water is possible and emphasizes searches for structures that resemble cells in terran organisms. It is possible, however, that life exists that is based on chemical reactions that do not involve carbon compounds, that occurs in solvents other than water, or that involves oxidation-reduction reactions without oxygen gas. To assist NASA incorporate this possibility in its efforts to search for life, the NRC was asked to carry out a study to evaluate whether nonstandard biochemistry might support life in solar system and conceivable extrasolar environments, and to define areas to guide research in this area. This book presents an exploration of a limited set of hypothetical chemistries of life, a review of current knowledge concerning key questions or hypotheses about nonterran life, and suggestions for future research.

Inside the epic quest to find life on the water-rich moons at the outer reaches of the solar system Where is the best place to find life beyond Earth? We often look to Mars as the most promising site in our solar system, but recent scientific missions have revealed that some of the most habitable real estate may actually lie farther away. Beneath the frozen crusts of several of the small, ice-covered moons of Jupiter and Saturn lurk vast oceans that may have existed for as long as Earth, and together may contain more than fifty times its total volume of liquid water. Could there be organisms living in their depths? Alien Oceans reveals the science behind the thrilling quest to find out. Kevin Peter Hand is one of today's leading NASA scientists, and his pioneering research has taken him on expeditions around the world. In this captivating account of scientific discovery, he brings together insights from planetary science, biology, and the adventures of scientists like himself to explain how we know that oceans exist within moons of the outer solar system, like Europa, Titan, and Enceladus. He shows how the exploration of Earth's oceans is informing our understanding of the potential habitability of these icy moons, and draws lessons from what we have learned about the origins of life on our own planet to consider how life could arise on these distant worlds. Alien Oceans describes what lies ahead in our search for life in our solar system and beyond, setting the stage for the transformative discoveries that may await us.