Current evidence indicates that life initiated on Earth just as soon as physical conditions permitted. We know that Earth-like planets are common in our Milky Way galaxy. But is there life on these planets, or is life on our Earth a unique phenomenon? Mars may also once have been habitable. Europa and Enceladus may hide oceans of liquid water below their icy surfaces. Are any of these locations suitable habitats for life? What physical conditions does life require to start and to flourish, and where are the settings to find such conditions?
These are the questions at the focus of Co-Evolution of Life and Planet.