As founding director of Cornell University's Carl Sagan Institute, astrophysicist Lisa Kaltenegger built a team of tenacious scientists from many disciplines to create a uniquely specialized toolkit to find life on faraway worlds. In this book, she demonstrates how we can use our homeworld as a Rosetta Stone, creatively analyzing Earth's history and its astonishing biosphere to inform this search. With infectious enthusiasm, she takes us on an eye-opening journey to the most unusual exoplanets that have shaken our worldview - planets covered in oceans of lava, lonely wanderers lost in space, and others with more than one sun in their sky! And the best contenders for Alien Earths. We also see the imagined worlds of science fiction and how close they come to reality. We live in an incredible new epoch of exploration.