For many thousands of years, human beings have been asking themselves whether they are more frightened of being alone in the universe or of the thought that there is someone else out there. Over the past few decades, however, we have moved from imagination to action, exploring the cosmos using new techniques, often with surprising results. Numerous fascinating but little known facts have emerged – for example, that every year many rocks from Mars fall on the Earth, that one of our amino acids has been found in the coma of a comet, and that some of the known thousands of extrasolar planets are similar to our own. There are further exciting and important discoveries around the corner that will cast more light on the great enigma of how life started on Earth. In this intriguing book, one of the World leading researchers in astrophysics and space science examines fundamental questions concerning life on Earth and the rest of the cosmos in an accessible and stimulating way.