It's one of the most important and fascinating questions human beings can ponder, and astrobiology is the emerging field of science that tries to answer it.
Astronomer Rhodri Evans gives an expert overview of our current state of knowledge, looking at how life started on Earth, considering other places in the Solar System that might harbour life, then discussing possible Earth-like 'exoplanets' orbiting stars further out into our galaxy - and what future missions and studies will tell us about extraterrestrial life there.
Along the way the book answers some key questions: How can we answer Fermi's paradox ('Where is everybody?')? Is water essential for life, or just a best bet for finding it? And how will we know when we find alien life, if it doesn't follow the same principles as Earth life?