Describing the most recent discoveries made with space exploration technology, including the Kepler space telescope, the Mars Curiosity rover, and the New Horizons probe, astronomer Jon Willis asks readers to consider five possible scenarios for finding extraterrestrial life. He reviews what we know and don't know about the life-sustaining potential of Mars's subsoil ice and the water-ice moons Europa and Enceladus. He also looks at Saturn's moon Titan through the lens of our own planet's ancient past. In this concise yet far-reaching volume, Willis even looks beyond our solar system, investigating the top candidates for a "second Earth" in a myriad of exoplanets.