April 2010 marks the 20th anniversary of one of the most important scientific tools ever employed by humanity, the Hubble Space Telescope. Hubble is the most celebrated celestial observer since Galileo assembled his first optical instruments. Theoretical physicist and astronomer Lyman Spitzer realized that our atmosphere was an imperfect window on the universe and he was the first person to propose the idea of placing a large telescope in orbit, free of the obstacles that clouded ground-based observatories. He was the driving force behind the development of what would eventually become Hubble. Named after the trailblazing astronomer Edwin P. Hubble, the space-based telescope has revolutionised astronomy by providing unprecedented deep and clear views of the universe, ranging from our own solar system to extremely remote fledgling galaxies formed not long after the Big Bang more than 13 billion years ago. Beyond its scientific contributions, 20 years of Hubble research and imagery have had a profound impact on the world's imagination and spiritual growth.The purpose of the book is to celebrate two decades of astronomical, scientific and technological breakthroughs as told through historic and glorious photographs. ''Hubble: A Journey through Space and Time'' features a collection of Hubble's most important images, as well as a section on the five successful manned missions that have kept the observatory functioning. Hubble's top 20 discoveries will be described in commentaries by notable scientists. Mission astronauts will contribute their reminiscences as well.