Galileo Galilei's Sidereus Nuncius is arguably the most dramatic scientific book ever published It announced new & unexpected phenomena in the heavens "unheard of through the ages" revealed by a mysterious new instrument Galileo had ingeniously enhanced the rudimentary "spyglasses" that appeared in Europe in 1608 & in the autumn of 1609 he pointed his new instrument at the sky revealing astonishing sights mountains on the moon fixed stars invisible to the naked eye individual stars in the Milky Way & four moons around the planet Jupiter These discoveries changed the terms of the debate between geocentric & heliocentric cosmology & helped ensure the eventual acceptance of the Copernican planetary system Albert Van Helden's beautifully rendered & eminently readable translation is based on the Venice 1610 edition's original Latin text An introduction conclusion & copious notes place the book in its historical & intellectual context & a new preface written by Van Helden highlights recent discoveries in the field including the detection of a forged copy of Sidereus Nuncius & new understandings about the political complexities of Galileo's work