Sidereus Nuncius, or The Sidereal Messenger

Galileo Galilei's Sidereus Nuncius announced new and unexpected phenomena in the heavens, revealed through a newly improved instrument. In autumn 1609, Galileo pointed his enhanced telescope at the sky and discovered mountains on the moon, fixed stars invisible to the naked eye, individual stars in the Milky Way, and four moons around Jupiter. These observations were previously unheard of and changed the debate between geocentric and heliocentric cosmology, helping establish acceptance of the Copernican planetary system. This edition presents Albert Van Helden's translation based on the original Latin text of the 1610 Venice edition. An introduction, conclusion, and extensive notes provide historical and intellectual context. A new preface by Van Helden discusses recent discoveries in the field, including the detection of a forged copy of Sidereus Nuncius and new understandings about the political complexities surrounding Galileo's work.