Are we alone in the universe? Right now we are in a period of unprecedented change that is taking us closer than ever to answering this fundamental question. A dizzying array of planets are being discovered orbiting alien stars and we've developed instruments so sensitive we can detect the weather systems on these new worlds. But do any harbour life? Geneticist Dr Adam Rutherford seeks to define what life is and Maggie Aderin-Pocock explores our chances of finding it in the universe.