The Invisible Sky tells the story of one of the most successful scientific instruments ever launched through the words of two of the scientists who were instrumental in the design and launching of the satellite, along with Hermann-Michael Hahn, an accomplished science journalist. This extraordianry collaboration chronicles the beginnings, early failures, construction, and deployment of the most famous of X-ray observatories in a highly readable account of cutting-edge science illustrated with spectacular colour images from ROSAT.