Each night, we are able to gaze up at the night sky and look at the thousands of stars that stretch to the end of our individual horizons. But the stars we see are only those that make up our own Milky Way galaxy—but one of hundreds of billions in the whole of the universe, each separated by inconceivably huge tracts of empty space. In this book, astronomer James Geach tells the rich stories of both the evolution of galaxies and our ability to observe them, offering a fascinating history of how we’ve come to realize humanity’s tiny place in the vast universe. Taking us on a compelling tour of the state-of-the-art science involved in mapping the infinite, Geach offers a first-hand account of both the science itself and how it is done, describing what we currently know as well as that which we still do not. He goes back one hundred years to when scientists first proved the existence of other galaxies, tracking our continued improvement in the ability to collect and interpret the light that stars in faraway galaxies have emitted through space and time. He discusses examples of this rapidly accelerating research, from the initial discovery that the faint “spiral nebulae” were actually separate star systems located far beyond the Milky Way to the latest observations of the nature of galaxies and how they have evolved. He also delves into the theoretical framework and simulations that describe our current “world model” of the universe. With one hundred superb color illustrations, Galaxy is an illuminating guide to the choreography of the cosmos and how we came to know our place within it that will appeal to any stargazer who has wondered what was beyond their sight.

When it comes to mapping the Milky Way, scientists know one thing for sure. They know that there is still a lot that they do not know! Discover how they study the Milky Way, and learn about the galaxy that we call home. Created in collaboration with the Smithsonian Institution, this Smithsonian Informational Text builds students' reading skills while engaging their curiosity about STEAM topics through real-world examples. It features a hands-on STEAM challenge that guides students through every step of the engineering design process and is perfect for makerspace activities. It makes STEAM career connections by providing a glimpse into the lives of real-life Smithsonian employees currently working in STEAM fields. Discover engineering innovations that solve real-world problems with this book that touches on all aspects of STEAM: Science, Technology, Engineering, the Arts, and Math!

When it comes to mapping the Milky Way, scientists know one thing for sure. They know that there is still a lot that they do not know! Discover how they study the Milky Way, and learn about the galaxy that we call home. Created in collaboration with the Smithsonian Institution, this Smithsonian Informational Text builds students' reading skills while engaging their curiosity about STEAM topics through real-world examples. It features a hands-on STEAM challenge that guides students through every step of the engineering design process and is perfect for makerspace activities. It makes STEAM career connections by providing a glimpse into the lives of real-life Smithsonian employees currently working in STEAM fields. Discover engineering innovations that solve real-world problems with this book that touches on all aspects of STEAM: Science, Technology, Engineering, the Arts, and Math!

A grand tour of our dynamic home galaxy This book offers an intimate guide to the Milky Way, taking readers on a grand tour of our home Galaxy's structure, genesis, and evolution, based on the latest astronomical findings. In engaging language, it tells how the Milky Way congealed from blobs of gas and dark matter into a spinning starry abode brimming with diverse planetary systems—some of which may be hosting myriad life forms and perhaps even other technologically communicative species. William Waller vividly describes the Milky Way as it appears in the night sky, acquainting readers with its key components and telling the history of our changing galactic perceptions. The ancients believed the Milky Way was a home for the gods. Today we know it is but one galaxy among billions of others in the observable universe. Within the Milky Way, ground-based and space-borne telescopes have revealed that our Solar System is not alone. Hundreds of other planetary systems share our tiny part of the vast Galaxy. We reside within a galactic ecosystem that is driven by the theatrics of the most massive stars as they blaze through their brilliant lives and dramatic deaths. Similarly effervescent ecosystems of hot young stars and fluorescing nebulae delineate the graceful spiral arms in our Galaxy's swirling disk. Beyond the disk, the spheroidal halo hosts the ponderous—and still mysterious—dark matter that outweighs everything else. Another dark mystery lurks deep in the heart of the Milky Way, where a supermassive black hole has produced bizarre phenomena seen at multiple wavelengths. Waller makes the case that our very existence is inextricably linked to the Galaxy that spawned us. Through this book, readers can become well-informed galactic "insiders"—ready to imagine humanity's next steps as fully engaged citizens of the Milky Way.

A theoretical astrophysicist explores the ideas that transformed our knowledge of the universe over the past century. The cosmos, once understood as a stagnant place, filled with the ordinary, is now a universe that is expanding at an accelerating pace, propelled by dark energy and structured by dark matter. Priyamvada Natarajan, our guide to these ideas, is someone at the forefront of the research—an astrophysicist who literally creates maps of invisible matter in the universe. She not only explains for a wide audience the science behind these essential ideas but also provides an understanding of how radical scientific theories gain acceptance. The formation and growth of black holes, dark matter halos, the accelerating expansion of the universe, the echo of the big bang, the discovery of exoplanets, and the possibility of other universes—these are some of the puzzling cosmological topics of the early twenty-first century. Natarajan discusses why the acceptance of new ideas about the universe and our place in it has never been linear and always contested even within the scientific community. And she affirms that, shifting and incomplete as science always must be, it offers the best path we have toward making sense of our wondrous, mysterious universe. “Part history, part science, all illuminating. If you want to understand the greatest ideas that shaped our current cosmic cartography, read this book.”—Adam G. Riess, Nobel Laureate in Physics, 2011 “A highly readable, insider’s view of recent discoveries in astronomy with unusual attention to the instruments used and the human drama of the scientists.”—Alan Lightman, author of The Accidental Universe and Einstein's Dream

When it comes to mapping the Milky Way, scientists know one thing for sure. They know that there is still a lot that they do not know! Discover how they study the Milky Way, and learn about the galaxy that we call home. Created in collaboration with the Smithsonian Institution, this Smithsonian Informational Text builds students' reading skills while engaging their curiosity about STEAM topics through real-world examples. It features a hands-on STEAM challenge that guides students through every step of the engineering design process and is perfect for makerspace activities. It makes STEAM career connections by providing a glimpse into the lives of real-life Smithsonian employees currently working in STEAM fields. Discover engineering innovations that solve real-world problems with this book that touches on all aspects of STEAM: Science, Technology, Engineering, the Arts, and Math!

This book is the first to provide a comprehensive, readily understandable report on the European Space Agency’s Gaia mission that will meet the needs of a general audience. It takes the reader on an exciting journey of discovery, explaining how such a scientific satellite is made, presenting the scientific results available from Gaia to date, and examining how the collected data will be used and their likely scientific consequences. The Gaia mission will provide a complete and high-precision map of the positions, distances, and motions of the stars in our galaxy. It will revolutionize our knowledge on the origin and evolution of the Milky Way, on the effects of mysterious dark matter, and on the birth and evolution of stars and extrasolar planets. The Gaia satellite was launched in December 2013 and has a foreseen operational lifetime of five to six years, culminating in a final stellar catalogue in the early 2020s. This book will appeal to all who have an interest in the mission and the profound impact that it will have on astronomy.