It's the biggest question we've ever faced, one that has fascinated generations of humans: do aliens exist? If they did, what would they look like? How would they think? And what would it mean for us if we found them? Here, Professor Jim Al-Khalili blasts off in search of answers. Featuring twenty pieces by top scientists and experts in the field including Martin Rees, Ian Stewart and Adam Rutherford, Aliens covers every aspect of the subject, from alien consciousness to the neuroscience behind alien abductions. And along the way he'll cover science fiction, the probability of us finding extra-terrestrial life, and whether recently-discovered exoplanets might support life. Engaging, authoritative and filled with scientific insights fresh from the far edges of the galaxy, Aliens is the perfect book for anyone who has ever looked up into the starry sky and wondered: are we alone?