Interest in exoplanets--the worlds of other stars--is not new. From the late 17th century until the end of the 19th, almost all educated people believed that the stars are suns surrounded by inhabited planets--a belief that was expressed not in science fiction, but in serious speculation, both scientific and religious, as well as in poetry. Only during the first half of the 20th century was it thought that life-bearing exoplanets are rare. This is not a science book--rather, it belongs to the category known as History of Ideas. First published by Atheneum in 1974, it tells the story of the rise, fall, and eventual renewal of widespread conviction that we are not alone in the universe. In this 2012 updated edition the chapters dealing with modern speculation have been revised to reflect the progress science has made during the past 40 years, including the actual detection of planets orbiting other stars. However, it is not intended to be more than a brief introduction to today's views; its focus is on little-known facts about those of the past. Why should we care what our forebears believed? Now, the question of ET life is a matter for investigation by science. Yet it's significant that most educated people of past centuries were convinced that other inhabited worlds exist, without any scientific evidence whatsoever. This historical fact reveals that human beings have an instinctive sense of kinship with the wider universe and a desire to see the realms that lie beyond this one small planet--and perhaps, eventually, to go there. Our ancestors conceived of such voyages only in a spiritual sense, as occurring after death. But we who have taken our first small steps into space are aware that our descendants may set foot on the worlds of other suns. Just as in the 17th century people were initially upset by the new knowledge that the stars are suns scattered in space rather than lights fixed to a nearby sphere, the growing awareness that Earth is not safely isolated from whatever lies beyond makes many of our contemporaries uneasy. Thus today's predominant feelings about spaceships are ambivalent. Nevertheless, if an impulse toward belief that we are not alone in the universe is indeed an innate characteristic of human beings, as the past spread of belief in inhabited exoplanets suggests, we can be sure that those who follow us will not turn back from becoming spacefarers.

A Note from the Author: On August 24, 2006, at the 26th General Assembly of the International Astronomical Union (IAU) in Prague, by a majority vote of only the 424 members present, the IAU (an organization of over 10,000 members) passed a resolution defining planet in such a way as to exclude Pluto and established a new class of objects in the solar system to be called "dwarf planets," which was deliberately designed to include Pluto. With the discovery of Eris (2003 UB313)—an outer solar system object thought to be both slightly larger than Pluto and twice as far from the Sun—astronomers have again been thrown into an age-old debate about what is and what is not a planet. One of many sizeable hunks of rock and ice in the Kuiper Belt, Eris has resisted easy classification and inspired much controversy over the definition of planethood. But, Pluto itself has been subject to controversy since its discovery in 1930, and questions over its status linger. Is it a planet? What exactly is a planet? Is Pluto a Planet? tells the story of how the meaning of the word "planet" has changed from antiquity to the present day, as new objects in our solar system have been discovered. In lively, thoroughly accessible prose, David Weintraub provides the historical, philosophical, and astronomical background that allows us to decide for ourselves whether Pluto is indeed a planet. The number of possible planets has ranged widely over the centuries, from five to seventeen. This book makes sense of it all—from the ancient Greeks' observation that some stars wander while others don't; to Copernicus, who made Earth a planet but rejected the Sun and the Moon; to the discoveries of comets, Uranus, Ceres, the asteroid belt, Neptune, Pluto, centaurs, the Kuiper Belt and Eris, and extrasolar planets. Weaving the history of our thinking about planets and cosmology into a single, remarkable story, Is Pluto a Planet? is for all those who seek a fuller understanding of the science surrounding both Pluto and the provocative recent discoveries in our outer solar system.

For more than a century, Mars has been at the center of debates about humanity’s place in the cosmos. Focusing on perceptions of the red planet in scientific works and science fiction, Dying Planet analyzes the ways Mars has served as a screen onto which humankind has projected both its hopes for the future and its fears of ecological devastation on Earth. Robert Markley draws on planetary astronomy, the history and cultural study of science, science fiction, literary and cultural criticism, ecology, and astrobiology to offer a cross-disciplinary investigation of the cultural and scientific dynamics that have kept Mars on front pages since the 1800s. Markley interweaves chapters on science and science fiction, enabling him to illuminate each arena and to explore the ways their concerns overlap and influence one another. He tracks all the major scientific developments, from observations through primitive telescopes in the seventeenth century to data returned by the rovers that landed on Mars in 2004. Markley describes how major science fiction writers—H. G. Wells, Kim Stanley Robinson, Philip K. Dick, Edgar Rice Burroughs, Ray Bradbury, Robert Heinlein, and Judith Merril—responded to new theories and new controversies. He also considers representations of Mars in film, on the radio, and in the popular press. In its comprehensive study of both science and science fiction, Dying Planet reveals how changing conceptions of Mars have had crucial consequences for understanding ecology on Earth.

Astronomers are on the verge of answering one of our most profound questions: are we alone in the universe? The ability to detect life in remote solar systems is at last within sight, and its discovery—even if only in microbial form—would revolutionize our self-image. Planet Hunters is the rollicking tale of the search for extraterrestrial life and the history of an academic discipline. Astronomer Lucas Ellerbroek takes readers on a fantastic voyage through space, time, history, and even to the future as he describes the field of exoplanet research, from the early ideas of sixteenth-century heretic Giordano Bruno to the discovery of the first exoplanet in 1995 to the invention of the Kepler Space Telescope. We join him on his travels as he meets with leading scientists in the field, including Michel Mayor, who discovered the first exoplanet, and Bill Borucki, principal investigator for NASA’s Kepler mission. Taken together, the experiences, passion, and perseverance of the scientists featured here make the book an exciting and compelling read. Presenting cutting-edge research in a dynamic and accessible way, Planet Hunters is a refreshing look into a field where new discoveries come every week and paradigms shift every year.

The entrepreneur/podcaster and the bestselling author of Forks Over Knives serve up delicious planet-friendly, vegan recipes from chefs and innovators. From Nil Zacharias, the cofounder of multiple online platforms focused on the plant-based food space, and Forks Over Knives author Gene Stone, Eat for the Planet Cookbook is a delicious, informative guide to eating vegan—featuring 75 recipes from some of the world’s greatest plant-based chefs, businesses, and influencers. These contributors range from vegan chefs and influencers such as Fran Costigan and Derek Sarno, brands like Beyond Meat and Ripple Foods, and innovative plant-based restaurants such as Veggie Grill, Next Level Burger, and The Stanford Inn. With this exceptional collection of go-to recipes and insight from some of the most influential voices in the vegan world, Eat for the Planet Cookbook is an essential guide to eating responsibly and eating well.

Human health depends on the health of the planet. Earth’s natural systems—the air, the water, the biodiversity, the climate—are our life support systems. Yet climate change, biodiversity loss, scarcity of land and freshwater, pollution and other threats are degrading these systems. The emerging field of planetary health aims to understand how these changes threaten our health and how to protect ourselves and the rest of the biosphere. Planetary Health: Protecting Nature to Protect Ourselves provides a readable introduction to this new paradigm. With an interdisciplinary approach, the book addresses a wide range of health impacts felt in the Anthropocene, including food and nutrition, infectious disease, non-communicable disease, dislocation and conflict, and mental health. It also presents strategies to combat environmental changes and its ill-effects, such as controlling toxic exposures, investing in clean energy, improving urban design, and more. Chapters are authored by widely recognized experts. The result is a comprehensive and optimistic overview of a growing field that is being adopted by researchers and universities around the world. Students of public health will gain a solid grounding in the new challenges their profession must confront, while those in the environmental sciences, agriculture, the design professions, and other fields will become familiar with the human consequences of planetary changes. Understanding how our changing environment affects our health is increasingly critical to a variety of disciplines and professions. Planetary Health is the definitive guide to this vital field.