Why explore the universe? What is happening to our planet? What would a habitat on another planet look like? As part of the Principia Mission Space Diary project – supporting ESA Astronaut Tim Peake's mission to the International Space Station – Stephen Hawking asks some important questions about life on our planet, and life beyond. Produced together with author Lucy Hawking, this video accompanies Chapter Five of the Principia Mission Space Diary. Sign up at principiaspacediary.org/sign-up to get exclusive access to the book, to download and complete at home or in the classroom. We also supply chapter-by-chapter Classroom Kits for teachers and educators with lots of resources, tips and information around the themes of space exploration and space history. Download and print your Principia Space Diary: http://principiaspacediary.org Tim Peake's Principia Mission: http://principia.org.uk Follow Tim Peake's mission: http://blogs.esa.int/tim-peake/ This project is produced by Curved House Kids and Lucy Hawking, and supported by the UK Space Agency, the European Space Agency, Queen Mary University of London and the London Science Museum. The space diary crew are author Lucy Hawking, Publisher Kristen Harrison at The Curved House, Professor Peter McOwan at Queen Mary University of London and illustrator Ben Hawkes. Narrated by Stephen Hawking Created by Lucy Hawking and Kristen Harrison Animated by Timothy Armstrong Filmed by Julian Mayers Music by Nina Hynes Produced by The Curved House (www.thecurvedhouse.com)